Do Passive Pre-Amps 'Limit' the Lower-Mids?


The following is from a comparison between an active (ARC-LS3) pre-amp and passive or pre-amp less system-operation; "Connecting a source-component directly to one's amp is no panacea for sonic realism, in my experience. It can even be a deterrent as the life and body of the sound can be sucked out of a system which is perfectly capable of LIFELIKE reproduction. What is left is a thoroughly competent sound that is crisp and clear but dry and analytical, and also bereft of lower-midrange body, liquid-lucidity and lifelike-musicallity..." The full 'review' is at: Active vs Passive Pre
waj4all
There are huge threads on passive preamps in this forum. read through them, especially the one on the Lightspeed Attenuator, which ends up being a lesson in passive preamps anyway. It will take some time, but it's a good place to start.
Tranny based preamps do NOT do what you describe. However, I have heard resistor based passives that do.

Shakey
Thanks for the responses: Shakey, if tranny-based passives really don't limit the lower-mids, then perhaps all passives should be so based. Components that slight any region of the audio-spectrum should perhaps be ruled-out for those of us in the search for ultimate realism, IMO. Poprhetor, I'm looking-up that Lightspeed thread. Thanks again!
not the well designed ones used in an appropriate system ... matching componenets in a passive based system can be more critical, but if done correctly the results will be every bit as good as with an active pre
Point understood!
Jrinkerptdnet,

"matching componenets in a passive based system can be more critical,"

Matching components in a passive based system IS more critical because you are basically building an entire system around an attenuator.
Rrog,

"Matching components in a passive based system IS more critical because you are basically building an entire system around an attenuator."

not if you are referencing a TVC passive

Jeff
TVC's have some theoretical advantages over a resistive passive attenuator, but there are still considerations not found with an active preamp.
All points are well taken. But I wonder if my ears are decieving me, or has anyone else actually heard a limiting of the lower-mids with passives, as compared to actives? For instance, Shakey has, but not with tranny-based passives. I just wonder how many others have actually compared the lower-mids of passives against that of actives. And which of these two types of pre-amps is 'fuller-toned' at the lower-mids - passive or active?
I consider Passive Preamps the "lazy bastards" of audio...I figure if I have to work hard, so should my preamp. It's only fair.
LOL! That's a good one. But then, passives could be the epitome of the paradigm; 'Don't work harder, work smater.' Just a thought.
what passives have you heard?? ones I have heard and owned from Bent Audio, Reference Line, Anodyne, Plinius, Poth Audio, FT Audio and Melos have all been excellent
I have heard lots of passives in my various systems over the years. I won't name them all, but they all have and are currently highly praised by passive fans. In each case I heard exactly what the poster described - I mean exactly!

Yes, I even had good synergy between the amp/passive and CD player and passive - still ended up with threadbare or thin sound that was certainly highly transparent and clean.

I am most perplexed that many seem to love passive preamps as my experiences with these units left me wanting. Many folks I respect love passive preamps so I guess it just comes down to personal sound preferences and PERFECT synergy. I suppose the perfect synergy thing as eluded me?

All one can do is try one in their system and make up their own mind. Just take care and be sure your current amp is a good candidate for a passive. Passive units do not like amps with a low input impedance (below 40-50K for instance)
Wai4all,
many share your impressions of passives. I`ll take a high quality active preamp any time for it`s more life like sound tonal realism.YMMV.
I've heard many a great passive pre and just as many poor ones (the Big Dog comes to mind as "sucks the life out" passive).
StereoKnight passives in the right system are wonderful IMHO.
Thanks for all the responses from those who advocate the use of passives, and from those who do not.

However, the main focus was not, necessarily, to see who liked passives or not, but to establish whether or not passives do limit the lower-mids, as I had previously found in my own system over several years. All responses are appreciated, nonetheless.

Grannyring, I see where you've had similar experiences to mine, with many passives (my personal expreience with them is less diverse). However, a previous poster asserts that the above may be true with many passives, but that transformer-based passives are superior in this regard, (I would assume he means that they're as full-toned as actives). My question to you is (if you're still there): Were any of the many passives you tried tranny-based? And was it your experience that those actually equaled, or approached, actives in their fullness of tone, and consequent realism, at the lower-mids? Anyone who has had such an experience - CharlesIdad, Rs507, Rrog, Jrinkerpdtnet, or any other - please feel free to jump in

[Bye the way, Grannyring, I've read your review of thr TRL Dude pre-amp - it was totally captivating. I congratulate you on your eloquence and articulation in positing your arguments. Almost everyone who reads that review may, perhaps, be convinced as to the veracity of your statements - I know I am! I'm not sure you've read my 'review' of my own ARC LS3 (linked at the top of this page) but I do agree with Martin Colloms, and others, that this might be one of the best (regardless of price) despite its reasonable price. Nevertheless, since I'm no fool, I also recognize that there are many which are better in several aspects, one of which (I believe) is the Coincident Statement. Until I read your review, I was convinced that the Coincident was the 'world's best' - now I'm not so sure. Have you, or has anyone you know of, compared the Dude to the Coincident? And if so, what was the result - ie; which is better overall, and which is better in what aspects of performance?]

Thanks again to all! Anyone else who's compared actives to passives, with a focus on the lower-mids performance of both, please do chime-in.
Waj4all,
I have`nt heard the TRL Dude but it`s well regarded. I`ve owned the Coincident Statement linestage for close to 2 years. The Statement is simply stunning, utterly natural tone/timbre with complete rendering of intricate overtones and harmonics. Perhaps one of the truly top tier performers in terms of openess, transparent and dynamic preamps available currently.

It does convey the pure emotion and beauty of music without exception. Really just a fabulous creation by designer Israel Blume.

I hope you have an opprotunity to hear it in yours or a very good system and judge for yourself. Be aware it has just two inputs, lacks remote control and is 70 pounds(2 chassis design). By the way it has an ultra low noise floor, you`ll hear the most subtle nuance and micro detail/dynamics(very compelling) and always organic in character.
Best Regards,
I was a big proponent of magnetic passives for quite some time and I still own one. They are less immune to some of the impedance matching problems associated with resistor passives. However, as has been stated many times in these forums, passives in general (magnetic and resistor) need more attention to system matching than their active or buffered counter parts.

As to whether magnetic are superior to resistive passives that is a preference thing. I don't think you'll find scientific proof one way or the other. Properly designed and implemented in the right system both should sound very close. These days though I'm using the Lightspeed attenuator which is a resistive passive, so that should tell you something about my preferences.

As for the thin sound, etc. it's not something I'm hearing, nor those who have heard my system. In addition, the only active preamp I have heard that I would take over a passive is the Concert Fidelity CF-080, at around $20k IIRC.

Now a magnetic passive that uses voltage gain....
***However, the main focus was not, necessarily, to see who liked passives or not, but to establish whether or not passives do limit the lower-mids,***

Can't be done. As has been pointed out, it has everything to do with the other components in your particular system; it's overall gain structure, and how you have voiced it.

Can passives "limit the lower-mids"? Sure they can. Just like some actives can make the lower-mids too fat. If you have tried several passives, and found that everyone of them has "limited the lower-mids", then I suspect that your particular system needs the gain offered by an active pre, and that the sum of your other components adds up to a sound that is on the lean side, and cannot afford (to your tastes) the removal of what the active pre adds to the mix. I use a Audio Synthesis "Passion" passive with a tubed phono stage, tube CD player, tube amps, and very efficient speakers with stellar results. When I replace the passive with my tubed preamp, the end result is a sound that is too thick, and fat through the lower-mids. Not to mention, much less transparent and detailed.

On the other hand, the same source components and amps driving my very inefficient Stax speakers absolutely need the extra gain that the active pre adds to the system. Otherwise, the sound with the passive is anemic, and threadbare.
Great point Frogman. I have only used speakers that are 87db efficient 2-40 ohm Soundlab, 92 db effecient/8 ohm Silverline and 90 db efficient 4 ohm Dali with a passive.

I know my amp/passive was a good match as well as my CD front end and the passive. I have wondered if the efficiency of the speaker also plays a role on the sound and success of a passive. Clio09 uses high efficiency speakers and likes his passive greatly. Perhaps the speaker plays a larger role in the successful utilization of a passive pre then I understand. How do we define highly efficient? Over 97 db and over 8 ohms?

Waj4all, I have not tried or heard the Coincident preamp, but like you find it very interesting. Love to compare it to a Dude someday! I have not tried a tranny based passive, but others like the Lightspeed and Placette.
As it has been mentioned before - it is all system dependent. I can speak for the TVCs. TVCs are attenuators and the the gain to the power amp is the key. If your CDP was putting out 2V and your amp's sensitivity is 2.5V, then this is not a good match. On the other hand if your amp's sensitivity is 1V, then this would be a good match. But you will have to be careful with cranking up the knob on the TVC, cause that extra voltage could blow your power amp and the speakers.

As for the loss of lower mid-range - not in my system!! I made careful match to the components in my system. So if I have to upgrade to a new CDP in future, I would want one with XLR output that puts out at least 3V. This would give my system more headroom, since I am not about "loud", but focused on "subtle".
If your CDP was putting out 2V and your amp's sensitivity is 2.5V, then this is not a good match.

Not necessarily based on my experience. My source is 2V and very low output impedance and I've had no problems or sound issues running it through either of my passive preamps into an Atma-Sphere S-30 which has a input sensitivity of 3V and a very high input impedance.

Speaking of impedance matching, I'm not as convinced these days the impedance ratio requirements for passives holds water. Not as much as I used to believe anyway based on the various types input impedance specs of the sources and amps I've been using with my passives.
Milpai, you seem to have missed my point. Most of us know the passive is often times dependent on proper matching of the amp and source. That is a given. But what about the speaker? High or low efficiency? What role does it play, if any, in making a passive work well in a system?
But what about the speaker? High or low efficiency? What role does it play, if any, in making a passive work well in a system?

This is an interesting point. Now you have me wondering.
****Can passives "limit the lower-mids"? Sure they can. Just like some actives can make the lower-mids too fat. .......................... I use a Audio Synthesis "Passion" passive with a tubed phono stage, tube CD player, tube amps, and very efficient speakers with stellar results. When I replace the passive with my tubed preamp, the end result is a sound that is too thick, and fat through the lower-mids. Not to mention, much less transparent and detailed.

On the other hand, the same source components and amps driving my very inefficient Stax speakers absolutely need the extra gain that the active pre adds to the system. Otherwise, the sound with the passive is anemic, and threadbare.****

Frogman, You seem to have answered the main question rather succinctly. And, perhaps, I should not have asked whether passives 'limit' the lower-mids, but rather whether actives and passives differ in their reproduction of the lower-mids. Resason being; the word 'limit' perhaps implies a 'fault', and this would be resisted by passive advocates, understandably. But your illustration of the performance of both actives and passives, in your system, indicates that a system can be tuned to sound adequate, in the lower-mids, with a passive (to suit ones preferences). And that the use of an active, in a system so tuned, causes the system to sound too 'warm', or 'thick' and 'fat', thru the lower-mids. You also indicate that disturbing this fine level of tune by the use of other speakers, with this system, causes it to sound 'anemic' and 'threadbare' with a passive, thus necessitating the use of an active (with its 'fuller response in this region) to compensate for this.

Correct me if I'm wrong, but all the above seems to suggest that the active is more naturally oriented towards a 'fuller' reproduction, of the lower-mids, than the passive (though the passive does have a slight advantage in clarity at higher frequencies, generally).

None of the other responses seem to directly contradict this theory so, perhaps, the answer to the question has presented itself thru your enlightening illustration. Thanks Frogman!

Regarding Shakeydeals assertion that transformer-based passives perform better, thru the lower-mids, than others, perhaps Clio9's response addresses that;

****I was a big proponent of magnetic passives for quite some time and I still own one. They are less immune to some of the impedance matching problems associated with resistor passives. .....
.....As to whether magnetic are superior to resistive passives that is a preference thing. I don't think you'll find scientific proof one way or the other. Properly designed and implemented in the right system both should sound very close. These days though I'm using the Lightspeed attenuator which is a resistive passive, so that should tell you something about my preferences.****

CharlesIdad, I doubt you not, about the Coincident. And Grannyring, I'm sure the Dude is absolutely awesome too. What with The Dude, Coincident, and perhaps on the next level, Dodd and Doge, I believe this is an exciting time to be an audiophile - even if we look only on the pre-amp front - not to mention all those passives, for those so inclined. Yep, great time to be an audiophile - absolutely!

Oh, and it's great to be here at the 'Gon too. As a newbie, my thanks goes out to y'all for being so accommodating
Grannyring,
I see what you mean now. I would speculate that a high efficiency speaker would work better than a low efficiency speaker with a passive. But again, this depends on the amp itself and not the pre-amp/TVC. The reason I speculate this is - high efficiency speakers require less power. So if the TVC was not putting out enough voltage to the amp and (hence) the amp is not putting out enough power, then, whatever little power it would put out should sound better through a high efficiency speaker than a low efficiency one.

Clio09,
I am not sure if the impedance matters with the type of TVC I own. When I was mentioning about sensitivity, I did not mean impedance.
Milpai, when I referenced impedance in my response it was just a general observation.

However, I do not feel sensitivity is as big an issue with matching a passive preamp in ones system. In fact, based on my testing it's a non issue. A 2V source can drive quite a few amps to clipping.
In my experience, the resistor based ones do. I had a Goldpoint precision attenuator between my CA 840C CD deck and two JC-1 power amps. The sound was exactly as you describe. These were sepcial 5K Ohm Goldpoints built to keep the lowest impedance to drive the power amps, but the downside is its also a low impedance to the CD deck.

Replacing the attenuator with an active preamp made a world of difference in lower midrange imaging, detail. And restored central bass punch that was not there with the attenuator. I suspect that it will be difficult to find an attenuator that will provide a low impedance to drive the cable capacitance and the power amps while not loading down the source driving the attenuator.
**** "In my experience, the resistor based ones do. I had a Goldpoint precision attenuator between my CA 840C CD deck and two JC-1 power amps. The sound was exactly as you describe."****

DR193449

So far as I'm aware, it seems they all do. I suppose, generally, the use of a passive, or active pre, depends on the type of sound one likes: Lean and analytical - passive. Or 'Full' and realistic - active.

Some passive advocates regard the passive's presentation as 'pure'. and the active's presentation as 'colored' or 'enhanced'. Be that as it may, it's perhaps safe to conclude that no passive, of whichever type, is as 'full' in the lower-mids as an active pre.

Whether the active's 'full' presentation is indeed a coloration, could be the topic of another discussion.

Perhaps!
Obviously, from many of the posts, they do, which indicates that there is not a good match between the passive preamp, and the amp in use. As I understand it,Resister based units will change what the amp is seeing base upon where the volume is set, and what resistor is in the audio path. The advantage of the TVC is that this variable is removed.

Assuming a good match between the source, the TVC, and the amplifer in question, it pretty much seems like a no brainer that a TVC will allow more of the music, or whatever else in in the signal to get to the amp. This is the very basis of the single ended amplifier designs that are so much more common these days, KISS, or fewer passive and active components to "muck up" the sound, as the Brits like to say. I am of the opinion that they work best with higher efficiency systems, such as I am using, but that is merely an opinion, not born out by extensive comparisons, as so far, only one system in my past experience has come close to what a single ended high efficiency system can provide the listener.
Assuming a good match between the source, the TVC, and the amplifer in question, it pretty much seems like a no brainer that a TVC will allow more of the music, or whatever else in in the signal to get to the amp.

Not in my experience. I own a TVC (Slagle), resistor, and LDR based passive. I'll give the TVC the advantage of being more forgiving with regards to impedance matching, but in my system the LDR sounds best.

One other note, the type of attenuator a passive uses also plays into the equation. A pot-in-the box using a simple Noble 25K pot can sound really good (see the Music Reference kits and pre-built units using this potentiometer). However, these, as well as series and ladder attenuators will in most cases add their own signature or create other issues that impact the sound. There is only one passive preamp I know of that takes the switch out of the equation.

Now has anyone tried a preamp that achieves voltage gain using an all passive design? Seems like this could be the ticket for those whose systems that need an active preamp (or for those who feel they prefer the "benefits" of an active preamp) but with a much simpler design.
Never met a passive i've enjoyed long term, list includes the much hyped lightspeed, TVC's, bent, you name it I tried it. Nothing takes the place of a good active for wringing the emotion out of the signal! Happy hunting!
I know one that definitely does NOT!!! Cost? $200. WTF kind of ultra-cheapo piece of crap could I be trying to peddle here?!!? Inexpensive it may be, but I can tell you it will absolutely kick to the curb every passive pre you've had the displeasure to come across AND every ACTIVE pre you've heard under $2,000. Just two restrictions: you give up remote control (but, most of them make you do) and you're pretty much confined to a single source system. So what the heck can it possibly be??...Scott Endler's Shunt Shotgun Attenuators, with surface mounted resistors. When properly installed there just isn't any sonic catagory that they can be said to fall down on...not one. I've used single-ended and Balanced, they're incredible, virtually at any price. They're better than an active pre because...well...there's nothing in the signal path except 2 resistors per channel. Think about it. Every diode, resistor, cap, etc. in your preamp right now is subtly distorting the signal...and, if they are all of first rate quality and sonically beyond reproach, then you probably paid a small fortune for it, yes? It's funny you should mention the lower mids, Waj4all. I just got finished with buying another round of AMD (Alan Maher designs) power conditioning products (something I can also recommend) which resulted in unpresedented gains in that area: a miryad of instrumental resonances and sonorities that were previously un-hinted at in my system. I seriously doubt that I would've been able to hear it all using an ordinary passive pre. Personally, I believe Shotgun attenuators simply solve THE underlying problem with passive pre's. Shotguns can ONLY be effective when applied DIRECTLY at (not 'into', but 'at') the input of a power amp - any intervening interconnect that's any longer than 6 inches begins to noticeably degrade the sound. All passive pre's themselves have the same sorts of sonic compromises the longer THEIR IC's are between them and the amp(!). Simply installing it in a box and locating pysically upsteam of the amp does absolutely NOTHING to solve the inherent capacitence/impedance problems introduced by the cables, no matter HOW good the cables are. It doesn't matter how expensive the cables are, there's simply NO WAY Ohm's Law can be satisfied that way. The concept of passive pre's is not necessarily flawed, but that kind of implementation of them necessarily is. Oh, if your preamp goes for $3,000 or more...sure, I'd say keep it, you're likely better off, but for anything under 2k, and maybe a few over that price, I'd say you definitely want to give these a try. Scott's still offers a 30-day gaurantee, if I recall...
Placing the passive attenuator at the amps input would be the way to go if at all possible. I have tried the Endler and EVS Ultimate attenuators and kept the EVS. They are stupid good for the money, but since I don't have cable issues the LDR sounds better to me. Then again maybe I need to break the EVS out of the box and give them another try.
Whether the active's 'full' presentation is indeed a coloration, could be the topic of another discussion.

The fullness of an active is not a coloration. The lack of bass that is typical of all PVCs is. It has nothing to do with the quality of the control, and everything to to with the variables of source impedance, the output impedance of the source at 20Hz, the value of the control, the setting of the control, the capacitance of the interconnect cables and the input impedance of the amp.

That's a lot of variables! Here are some other points so you can get an idea of how they play out: The lower the value of the volume control overall, the less detrimental effect it will have as you turn it down. However, the lower the overall value of the control, the harder it will be for the source to drive it. The higher the overall value of the control, the easier the source can drive it, but as you *turn down* the control, the series resistance instantly turns against you and you loose bass and impact right away.

With PVCs there is no way around this dilemma- that is why active preamps sound more 'full'- they can play bass properly!

Now to TVCs- TVCs solve a lot of PVC problems I just mentioned. They bring on some of their own. The transformer in this kind of control behaves the same way it does in any other transformer situation: it has a certain bandwidth and it has an ideal impedance to drive wherein it will have the least distortion due to ringing and other inductive effects.

To make this work, the TVC has to be very carefully designed so that it is properly loaded at all volume control settings. This is a bit of a trick! The reason is that a transformer *transforms* impedance- that is why they are so named.

When you use a particular setting on the control, it will express a certain ratio of the windings from input to output and thus your volume control setting. Maybe at that setting it is also properly loaded and so there is no ringing. Now the source impedance does not change and neither does the input impedance of the amp, nor the impedance of the cables (mostly expressed by capacitance). Because these other aspects are constants, as soon as you move to another control setting the loading is no longer correct. This will result in distortion due to ringing, or a loss of high frequencies. It may also result in the turns ratio no longer being properly expressed- indeed, with no load the transformer will express the inter-winding capacitance rather than the turns ratio.

Finally we have the issue of overall bandwidth. Transformers always express a compromise of low frequencies vs high frequencies- how well you can play bass will have an effect on how well the highs are played, in a nutshell. The smaller the transformer, the better the bandwidth, as a general rule of thumb. **However** to play bass to 20Hz, the circuit has to have bandwidth to 2Hz, else 20 Hz will not play correctly. Transformers have trouble going that low- in essence, you will not be hearing the deepest bass out of a TVC whereas an active preamp *should* be able to do 2 Hz no worries (our preamps go to 1 Hz). BTW the test for this is '20Hz square wave tilt', IOW the measure of how level the top of the square wave is. To play 20Hz correctly it should be unmeasurable.

Now its my opinion that the only reason PVCs and TVCs have made their way in high end audio has to do with how abysmal some active line stages actually are. But just because some line stages are obviously colored does not mean they **all** are, and price has nothing to do with it!
OK, maybe I should drop back 10 yards and punt… There are some things I neglected to say in my post above. I agree with you W.A.J. that most folks are for the most part dissatisfied with passive compared to active pre’s (which includes in my mind the sonic drawbacks you gave). And furthermore that most source/amp combinations, particularly among your average audiophiles (of which I’m perfectly willing to declare myself one), can perhaps often be thought of as something less than ideal. And yet again that active pre’s at their best can well be thought of as the kind of beasts that can simultaneously ‘elevate’ the performance of both source and amp alike, even demonstrably beyond what is available to each, in circumstances such as your own, when directly connected - while also possibly allowing them to ‘see’ each other on a more level playing field. I myself can’t recall ever running across anything that would seem to undermine or preclude any of all that. BUT…what I’m saying is this: what if all this, true as we take it to be, is not the WHOLE picture? What about those times when there can be said to be a synergistic match between source and amp to start with? Could this harbor at least the possibility that in that case the performance gap between those same passive and active pre’s within those systems could be said to narrow? Could passive pre’s in that instance then be thought of as being allowed (for once) to actually live up to the potential of their designs? That is, can the performance of a synergistic source-and-amp combo, when given an appropriately high quality passive pre, favorably compare to the performance of the source-and-amp combo, when given an appropriately high quality active pre? Can the synergy of the former pairing alone account for that difference? Does such a scenario tend to explain the few steadfast holdouts who insist that well-designed and executed passive pre’s offer real performance gains?? I certainly accept the notion that many, if not most, source/amp combo’s out there are likely subpar (as far as the best possible approach toward satisfying Ohm’s Law may go, anyway – even if I, and most of us, I suspect, can fail to reliably predict or perceive all the necessary parameters – real or theoretical – involved with it). But, I mean, nobody questions the performance issues when discussing the synergy (or lack thereof) in amp/speaker combo’s, yes? So why should we feel it somehow shouldn’t apply to source/amp combo’s as well? Maybe, as an owner of remarkably good-sounding shotgun shunt attenuators, it turns out I just happen to be one of the lucky few…? Good synergy all the way around?? I can say this: I have NO apparent bass performance issues…none, zero, zilch, zippo…plenty of slam, articulation, definition, dynamics, swing and, yes, authority! I have NO lower midrange issues either…as I say, natural instrumental resonances and sonorities, rich harmonics…hollow, wooden instrument bodies, all manner of woodwinds, the full measure of the golden sonorities of lower brass and piano that naturally clangs and truly hammers and glows…check, check and check… Currently, BOTH of those categories I consider to be definite system strengths for me – not weaknesses – strengths. Maybe the nearly $3,000 I’ve (gladly) paid for the power conditioning gear I’m using has something to do with it… Maybe passives are more susceptible to EMI/RFI than actives…I dunno. I certainly don’t doubt that you, W.A.J., have heard what you’ve heard any more than I doubt that I’ve heard what I’ve heard in my own system. But, since I can’t prove any of this in a court of Ohm’s Law, I suppose I can only wish I could audition your system and hear things for myself and you do same with mine. I certainly feel like there’s an explanation out there that would account for both our experiences to a large degree, but for now at least I’m at a loss to recognize it.
What about those times when there can be said to be a synergistic match between source and amp to start with? Could this harbor at least the possibility that in that case the performance gap between those same passive and active pre’s within those systems could be said to narrow? Could passive pre’s in that instance then be thought of as being allowed (for once) to actually live up to the potential of their designs? That is, can the performance of a synergistic source-and-amp combo, when given an appropriately high quality passive pre, favorably compare to the performance of the source-and-amp combo, when given an appropriately high quality active pre? Can the synergy of the former pairing alone account for that difference?

The problem with synergies is that a weakness of one product is being balanced against a weakness in another product. A simple example is a dull preamp paired with a bright amplifier. Together they sound OK- in other situations those faults are revealed.

This scenario does not work. When a synergy is exploited in this manner, the result may have some good qualities but you will always have a system that is less transparent and less fulfilling than if the individual components did not require such manipulation to begin with!
Hi Atmasphere. I understand the example of synergy you present, but that's not really the kind I was referring to above. In fact, I tend to agree with you that the example may really represent something subpar. I don't really mean the process in which we more or less try to 'shoehorn' amps into their respective speaker mates. This kind of scenario usually starts with us selecting, say, a given amp and then going about the usual process of searching for or trying out different speakers until we find something either really good or, at least satisfactory. We may feel we've succeeded or that we've fallen short, or perhaps not really know. But, there must be other examples of synergy out there in which people, if nothing else, have randomly stumbled across truly excellent combo's (with performance well above what's usually encountered) just by chance. I know of such matches. Brick and Mortar retailers for example are not unfamiliar with them. I once had a vintage Luxman amp mated with my old pair (which I still use) of Magnat 3-way towers (MSP-120) that seemed made in heaven. Older audiophiles can likely tell you similar stories of having had such a pairing only to later regret having had to split them up for whatever reason. My retailer didn't know of the match before he stocked his store with each brand, but he and his customers soon discovered it. There are many 'famous' matches out there. Just ask most Maggie owners what their speakers really seem to prefer. Of course, subjectively it may be hard to ferret out which are the 'best' and which pairings may truly fall into that category and which don't, but my point is that they naturally tend to exist, just as surely as bad ones are known to - and all the average/acceptable ones inbetween. That was really the basis of my questioning.
OK, I have what is probably a stupid question. I've been using passives for a long time now. McCormack TLC, Endler, Promitheus Ref 4, and now a Promitheus Signature. I like the TVC's a lot. I've recently been auditioning speakers, and I've had numerous systems come across with an unnatural level of dynamics. They just don't sound like any live music I have ever heard. And this is with my music, so it is not the recording. All the stuff I have auditioned has used an active pre, and I have found myself wanting to bring my own front end into the store so I can understand what the speakers actually sound like. Is it possible an active can be responsible for an effect like this?
I wouldn't mind trying a really good active sometime, but my recent experience has given me pause.
I've recently been auditioning speakers, and I've had numerous systems come across with an unnatural level of dynamics. They just don't sound like any live music I have ever heard. And this is with my music, so it is not the recording. All the stuff I have auditioned has used an active pre, and I have found myself wanting to bring my own front end into the store so I can understand what the speakers actually sound like. Is it possible an active can be responsible for an effect like this?

It could be the active pre, but it could easily be any of the other components or just bad overall synergy. Hard to say without knowing the systems you are listening too. I think Ralph might have been on to something interesting earlier when he said the popularity of passive preamps has more to do with the fact that many active preamps are abysmal.

Is it that active preamp designers for the most part are incompetent when it comes to understanding what is required from a design perspective to make the result non-colored and transparent? Is it a cost issue where designers have to compromise to meet a price point and thus compromise the design and resulting sound? Is it that some designers develop a house sound they like (as do their customers) so they design to that requirement? Is it something else?

I'd like to know what active preamps can be considered non-colored and transparent, as well as what aspects of their design from a technical perspective make it so. Also, what are their price points? I think I have identified one already that I'll most likely be picking up, but I'd be interested in hearing about others and again, not opinions, but what technically allows the resulting sound to be non-colored and transparent.
Thanks Clio.
I guess I'm also wondering if any one else has experienced this "too dynamic" phenomenon. I'd guess about half of the systems I've heard have been "too dynamic" in the sense of being quite unnatural, and I've heard this in more than one shop. Has anyone else heard anything like this?
Maybe it is as you say bad synergy, but really, can the brick and mortar shops be that bad at putting a system together?
On the other hand, I heard an Esoteric/BAT/Wilson system that was just wonderful. The only thing I've heard so far that was to my ears pretty much flawless.
Brownsfan, It is a common experience to hear things at dealers that might sound unnatural. Poor acoustics, other speakers in the room and other factors are easy contributors. Any decent dealer will allow you to bring in your front end to help out with an audition though.

Clio09, a preamp's line section has 4 functions:
select input
control volume
add any needed gain
control the interconnect cable

PVCs do the first two and most active line sections do three. Very few do all four, mostly from what I can tell due to the fact that the designers are unaware of the fact of the 4th function. The result is an otherwise neutral design's capabilities go untapped due to the coloration of the cable. Add to that the colorations that are common pitfalls with a lot of designs and you have a line stage that is a good attempt but nevertheless gets poor results.

See y'all at RMAF!
Waj4all, your review was very thoughtful. You hit the nail on the head regarding the inability of many speakers and amps to reproduce lower midrange body. It's funny to see how we audiophiles generate an ocean of words addressing a "problem" that is not really THE problem.