Is the source or preamp flawed?

In Robert Duetsch's follow-up of the CAT SL1 Renaissance Black Path Edition Preamp in the Dec issue of Stereophile, he compared the sound of the PS Audio DS dac direct to the power amps vs. through the CAT and found that it was no contest with the latter combination clearly superior and this was immediately apparent.
So, is either component here flawed - source or preamp, or is it something else in the chain - power amp, speakers, cables, etc?
I have the PS Audio Direct Stream DAC and ran it straight into the power amp. It was OK but needed something more. Paul McGowan at PS Audio used to proclaim how much better it "was" to not use a preamp and run the DAC directly into the power amp. He later was eating his words after he discovered how much better the sound was when he cabled up an Aesthetic Calypso tube preamp.

I am using an Eastern Electric Avant tube preamp and the difference is like milk toast to gourmet. More dimension, better imaging and image density, more tonal saturation...
Neither is flawed. The system works fine with, or without the preamp. Its a subjective call. There is no right or wrong answer. You may listen to the same system and like it better without the preamp.
Zd542 is correct in my opinion, it truly depends on the desires and preference of a given listener. You could have 10 very experienced liseners in the comparison such as this, five would say the direct source to amp is better and the other five would say sound is better with installation of the preamp. In my own experience more often than not I find a high-quality preamp to make a substantial improvement, but again that's just my listening perspective.
I used to listen with source direct to power amp. One day, I tried a preamp in between and there was no turning back. The improvement was immediate and substantially so.
I have read Paul's post on the DS dac and tge Aesthetix Calypso. He gave some explanation as to how a preamp can improve the sound and he now has the great Bascom King to design the BHK preamp in-house. Even Mr King himself heard the vast improvement with preamp in the chain but he admitted that he just could not explain or understand why.
In Stereophile's Dec issue, JA described the Ayre KXR Twenty preamp as making things sound better than no preamp in the chain.
I certainly agree with the last couple of posts that a good active preamp just seems to bring it all together. I have had the opportunity to own a tricked out Tortuga LDR passive over the past 6 months. I like it in my system and it has been fun. I also liked the Lightspeed LDR in my system. It really comes down to personal preference for sure. I prefer the TRL Dude to these passives, but after hearing all three over a long period of time I have come to understand why some like direct and passives better.

I am building a very interesting active tube preamp and will use my Tortuga LDR as the attenuator since it is so perfectly neutral. I am building the preamp in a way that allows me to easily remove the LDR to A/B compare to the tube active preamp. Since the LDR attenuator is so neutral I will essentially hear what the active tube stage brings to the party and what it may give up. This should prove very interesting.

The active tube stage is being built to get the very best out of the 6sn7 tube. I like this tube's sound. True dual mono, with twin b+ and filament trannys, twin IECs, twin filament filters, twin plate supply filters that are regulated, no electrolytics in the preamp, and top quality parts throughout.

Forgot to mention SS rectification with FRED bridge rectifiers and NOS Western Electric We16ga signal wire. Even the power supply uses 14 gauge, solid core Neotech copper wire.

I hope to finish this in one more week and start comparing to Tortuga LDR on its own and the same LDR utilized as an attenuator in the active.
With your audio engineering background, can it ever be explained how adding a preamp in the signal path can improve the sound given that theoretically less is expected to be more?
I know this has got a lot of experts in the field scratching their heads for some time now and it may just remain a mystery forever but as usual, our minds do itch to solve mysteries like these. :)
When I first received the PS Audio DSD my initial thoughts were it had more detail connected direct compared to having my Parasound JC 2 BP in the chain. Upon extended listening I felt I was missing dynamics and the music had a thin sound. I replaced the DSD with the Bricasti M1 DAC. It was much better direct than the DSD, but it was still missing something. I currently have a Jeff Rowland Aeris DAC and will never go direct again. I hate the saying, but I think a preamp puts some "meat on the bones."
I tried this experiment (using a preamp in the chain, or going direct) using my McIntosh MC275 for the amplifier, and my Wadia 27 DAC as the source. Both of these units have fully balanced as well as single ended inputs/outputs respectively.

And I discovered something really interesting. With a single ended hookup configuration, using a *good preamp in the path yielded better sonics than a direct hookup. However, using a balanced hookup, and running the source direct into the amp, produced the best sonics of all (to my taste, of course ;~) I don't know enough EE to speculate why, however.

* I did the experiment using two very good preamps, just because they were available at the time. One ss, and one tube; both of them with either single ended, or fully balanced inputs/outputs.
Yes, the phrase has been used way too often but to me, that seems to be the only way to describe it. Of all the parameters that benefit from adding a preamp, "meat on the bones" is the one that starkly stands out right at the top of the list. Every other improvement is a distant second.

a pre-amp is the "heart" of any system. Get it right and you will be musically rewarded. Get it wrong, you will not be musically rewarded. Most important of all, which brand(s) of cabling are you planning to use?

Keep me posted & Happy Listening!
"11-28-15: Jon2020
With your audio engineering background, can it ever be explained how adding a preamp in the signal path can improve the sound given that theoretically less is expected to be more?"

This is also subjective. What makes for an improvement?
I am a DIY hacker! No professional for sure. Anyway, more meat on the bones is the big difference with a tube active. This has been true thus far in my systems. However, to some more "meat on the bones" is not a good thing.

I will be able to simply expound on the differences soon. That is all I can do. We aphiles have different tastes and desires in such things as tone, neutrality, staging etc...
Jon2020, what I was saying in my last post is I cannot give you a definitive answer to that question. I do not have any sort of electronics degree and simply have been reading tons of stuff on how to build tube gear of late.
The improvement is, er...."more meat on the bones"(dang, said it again!) which most aphiles would be able to hear straight away. But whether that is indeed your cup of tea, would be another matter altogether....

I am very happy with my current set-up using Kimber Select ic and sc. Not looking to change anything for a long time to come. Just itching to solve this mysyery, that's all ....

You must be reading a lot to build your own tube preamp. Keep us posted on the outcome of your upcoming experiment....

J. :)
The question that needs to be asked is why would a preamp improve the sound in the first place. It's not a source, so it by definition should not add signal.

Isn't a preamp about having multiple sources and a volume control? It's about control, not sound or signal - at least in terms of being a source.

The fact is if we agree a preamp is not a source, if you accept a preamp as not being a source, then by that definition if you add a preamp and the sound changes then anything that preamp does to the sound is in addition to the source signal or a taking away from the source signal.

At the end of the day it's probably a subjective call, like zd542 says, at least in terms of what sounds good to one person or another.

For me, I want the purest signal so I avoid active preamps.
Could you tell us what the 2 preamps are?
That you find going direct better than via the 2 preamps simply confirms what has been said many times - listen both ways and decide with your own ears what you prefer.
A few points to consider :-
1. There could be an impedance mismatch between the source and the 2 preamps and your power amp
2. The source is designed and optimised for direct use as would usually be indicated in the manual
3. That you find a balanced connection better than single-ended confirms that both source and power amp are fully balanced in design and optimised for balanced performance.

J. :)
" Meat on the bones" It may be an overused term but most people understand its meaning in regard to sound quality.
For most it suggests more tonal body, fullness, harmonic richness and dynamic contrast, macro and micro. Resulting in more tactile presence and gravitas.

However some proponents of direct or passive approach would consider these preamp attributes merely "colorations" and not true to the source. They will state passionately that although these colorations may be pleasing, they aren't "accurate" or neutral. In theory I understand this opinion, but not in actual listening reality.

The sonic attributes provided from high quality preamplifiers will render the music/sound more realistic and thus more natural to certain liseners. They seem to fill in added vital information that would otherwise be absent. This absence or subtraction resulting in a leaner, less fleshed out and complete sound. This could be interpreted as more transparency and clarity for some listeners.

So it seems there are two broad camps of listeners.
1, Accurate/neutral and true to the source and
2, Natural, organic and more like live sound.

Listeners will eventually determine which camp or group suits them best. As mentioned earlier this is why people can hear the same direct comparisons and reach opposing conclusions as to what sounds better. This debate won't ever yield a universal right answer.It's a matter of what sounds right to each listener.
"The question that needs to be asked is why would a preamp improve the sound in the first place."

If seasoned audio reviewers can come to some sort of consensus when they put in their votes for a "product of the year", we can trust their ears to hear an improvement over the original signal from the source with a preamp in the chain.
So, when an improvement is heard, can the above question ever be answered?
Jon2020 - your question asks...

- "can the above question ever be answered?"

That question is...

- "why would a preamp improve the sound in the first place"

The answer:
- that particular pre-amp provided the additional "qualities" that were a preference of that particular reviewer - that's all.

You might just find that another amp or DAC combo without that pre-amp is preferred by the very same reviewer.

It's subjective - maybe even to a given point in time...
- e.g. who knows, after a couple of years, the reviewer's hearing may change and they then prefer the sound without the pre-amp in the mix!

It may even change if the location of the audition was changesd

It's just a very fickle hobby(obsession) full of
- an individuals' personal preferences, plus
- a boatload of variables - components, room acoustics etc...
- that come together at the time of that particular review.


Answering your question from earlier in the thread, from a technical perspective, many of these issues have been discussed in the various threads dealing with active v. passive preamps. More particularly, whether inserting a preamp into the signal chain can improve performance as opposed to driving the amplifier "directly" from the source depends upon at least the following:

(1) The mechanism of attenuation used (in particular, there have been a number of comments regarding the use of digital attenuation as reducing overall resolution)
(2) The quality of the output stage of the source
(3) The output impedance of the source
(4) The input impedance of the amplifier
(5) The impedance of the interconnect used between source and amplifier

Thus, inserting a preamp can result in better sound for a number of reasons, including: higher quality attenuator; source and amplifier impedance incompatibility (i.e., relatively high source impedance and relatively low amplifier input impedance) - which itself can be exacerbated by high cable capacitance; and lesser quality output stage of the source.

If they were all the mythical "perfect preamp" and sounded like "a straight wire with gain", then they would then all sound the same, as if you were direct connected from source to amps.

Why do all active preamps sound different? It's because they all colour the sound with different distortions.

They CANNOT add anything to the recorded music from the source that wasn't there to start with, they can only colour it with distortion, a bit like a synthesizer would do.

Those that say active preamps extract more detail, ambience or music from the source than direct connection are talking pure voodoo.
Those that say they like the colouration distortions that certain preamps bring to their system are being honest to themselves.

Cheers George
George, I agree with your remark
Those that say active preamps extract more detail, ambience or music from the source than direct connection are talking pure voodoo.
Those that say they like the colouration distortions that certain preamps bring to their system are being honest to themselves.
but it doesn't throw any more light on the subject at hand ;~)

The fact is that the (NOT particularly vast) majority of respondents seems to feel that having a preamp in the chain yields better results. I experienced BOTH kinds of "better" results (see my previous post) depending on whether I used single-ended or a (fully) balanced hookup configuration.

I'm only an 'amateur' electrical engineer, so not informed (enough) to speculate on why I got the results I did. Usually with something like this, it's (largely but not completely) about impedance matching. But there are other factors, like the effect of the buffering circuits in most preamps.

I also want to say (before someone inevitably asks ;~) that my 'preferred' sounding configuration (with preamp) in S.E. mode did not sound the same as my 'preferred' sounding configuration (direct) in BAL mode!

Re my equipment: I used a Levinson 26s for my ss preamp and an Atma-Sphere MP-3 for the tube unit. They are my two favorite preamps that I could ever afford!

My (digital) source is a Wadia 27 DAC. It has a very sophisticated volume control and Wadia designed it to be a direct source into an amplifier. (My McIntosh amp has volume controls on the S.E. inputs only, so I left those wide open to keep apples to apples ;~)

The most interesting part (for me) of setting up these A-B experiments, was making sure that the (generally accepted) optimal 1 o'clock preamp volume setting could be used with BOTH preamps AND with more or less the same level setting on the Wadia DAC. Finding a practical volume control setting with one's equipment, and for most of one's listening, is another area (along with impedance matching) that I think can have a lot of influence on (subjective) listening results. One reason I wish more preamps had a choice of 'default' gain settings (like the Levinson does.)

So what did I like best? Well, I have to say that if digital was my only source, I'd run my DAC direct into my amp (in fully balanced mode.) But that with so many sources, along with subwoofer and headphone amp connection requirements, that just wouldn't be very practical for me, and not worth the very small incremental improvement (in dynamics) I noticed I got by going direct.
Here we go.....
I mentioned audio reviewers. I should have added audio designers/engineers. In the latter group are Paul McGowan and Bascom King who have openly admitted to hearing a significant improvement with preamp in the chain. I would very much trust their ears too.
J. :)

11-29-15: Nsgarch
George, I agree with your remark

Yes, and just to further my post, most sources with solid state output stages, are as good some even better to be able to drive a poweramp and interconnect direct, than many preamps can.
In in case of tube preamps, most solid state sources will drive even better them.

As for quoting Paul McGowans turn around on this very subject, it's funny he should do this just before he released his new active preamp onto the market.

Cheers George
"Most important of all, which brand(s) of cabling are you planning to use?"

W/o getting into the active vs. passive debate (or the true to source or most pleasing sound or the theory vs practice debate), it seems to me that unless there is a gross mismatch, the brand of cabling one uses is the least significant element in this discussion.

Getting into that debate, it seems to be that the only thing that matters is what pleases your ears. All the rest is just the means for reaching the end of an emotionally satisfying listening experience. So this is a case where the ends fully justifies the means. IMO,YMMV, LSMFT, SQ3R.
Let's say that points 1 and 2 are all equal in an A/B comparison and that points 3 to 5 have been optimised impedance-wise for source, preamp and power amp,
What could then explain the improvement heard given that the celebrated audio engineers mentioned previously would have ensured that their in-house designs match one another?
J. :)

I don't know why passive is being bought into the subject.

Just to correct something, going direct as the OP did is not passive, it's still active as his PS Audio dac's volume is done before the active output buffer stage which is an active drive to the interconnects and poweramp/s

Cheers George
Paul McGowan initially penned his surprise when he heard improvements with the DS dac going through the Aesthetix Calypso preamp. That he went ahead to have an in-house preamp could be because he wanted to further optimise component matching to a higher level than with the Calypso.
J. :)
I don't accept the premise that direct source to amplifier delivers the audio signal fully intact. It may in fact deliver only a partial signal and the addition of a good preamp corrects these subtractions.

This thread and others reveal many lisners who find the preamp improves the sound.Better tone,harmonics,bass, dynamics and fleshed out images are just colorations? Really? Each active preamp does have its own sonic signature, agreed.

Run five different sources direct to amplifier, guess what? Five different sonic signatures amongst them as well. Each is distinct from the other direct source. Every audio device, part and component has a signature. MSB sounds different compared to DCS which again differs from Trinity or what ever brand you choose.

This is why the experienced contributors on this thread readily acknowledge it is pure preference and subjectivity that rule the day.
Regarding Paul McGowan, why is hard to acknowledge he simply heard improved sound with an active preamplifier added to his system. This is not a rare finding.
I think you got it.

So, the plausible explanation which is not unlike PMcG's, is that the source introduces colorations or distortions of its own and a high quality matching preamp ameliorates some if not all of these, to result in sonic improvement.

This doesn't seem too far-fetched. I could go along with this premise. IMHO, I think it's very fair to say that ALL sources introduce some kind of coloration or distortion of its own, just as does EVERY other component in the chain, cables included.

J. :)

If McGowans statement is correct.
"DirectStream is more than capable of driving the power amplifier directly."

Then it has an active output buffer which is as good if not better than most preamps outputs have, especially tube ones.

If not correct, then it must have something that is stopping it from driving a poweramp direct and not as good as he makes out, and will have the same problem driving interconnects and a preamps input stage, as the loads and design are very similar to a poweramps input stages.

Cheers George
The DS dac is just one example. There are many other sources reviewed in the pages of TAS, Stereophile, DAR, Audiostream, HiFi R&R, HiFi+, etc that sound better with preamp, to the seasoned ears of the reviewers.
I would go along with Charles' thoughts.
J. :)
IMHO, it can be said then that in general, all components in a system are flawed including the source, and that component matching or overall system synergy, ameliorates if not eliminates these flaws to the minimum, such that overall sonic performance is optimised.

J. :)

"component matching" "performance is optimised"

That is why there are electronic laws of "Ohm and Kirchoff" and others to be adhered to, by not doing is voodoo.

Cheers George
I would not consider ameliorating the flaws of a source to be voodoo.
It is very unlikely that one can find a "flawless" source to begin with, one that introduces ZERO coloration/distortion of its own.
Jon2020, that is well said.

By adding an expensive active preamp down the line to a flawed source, you can magically fix it with it's own set of colourations/distortions, "good luck with that."

What happens if the preamp is the mythical "prefect preamp" "sounding like straight wire with gain", then your hearing the flawed source for what it is, what then.
You change the source to one you do like the sound of.

Cheers George
Yes, there is no flawless source or flawless anything else when it comes to audio. Your logic and reasoning is on the mark. The notion that direct source to amplifier is ideal/perfect/flawless and thus can't be improved upon is a flawed premise. This approach may be preferred by some(which of course is fine)but it has its compromises as well.
Many thanks for all the input so far.
It's good to be able to have a healthy and open discussion like this while remaining civil and cordial.
Let's hope to hear more views from others on this rather contentious but very interesting issue.

J. :)
11-28-15: Nsgarch
I tried this experiment (using a preamp in the chain, or going direct) using my McIntosh MC275 for the amplifier, and my Wadia 27 DAC as the source. Both of these units have fully balanced as well as single ended inputs/outputs respectively.

And I discovered something really interesting. With a single ended hookup configuration, using a *good preamp in the path yielded better sonics than a direct hookup. However, using a balanced hookup, and running the source direct into the amp, produced the best sonics of all (to my taste, of course ;~) I don’t know enough EE to speculate why, however.

* I did the experiment using two very good preamps, just because they were available at the time. One ss, and one tube; both of them with either single ended, or fully balanced inputs/outputs.

I don’t find that surprising, Neil, although too many explanations are conceivable for **anyone** to do more than speculate as to the actual reason.

Changing between single-ended and balanced connections between two components of course changes many things at once: The design and configuration of the interface circuits in both components; how the grounds of the two components are interconnected; how signal return currents flow between the two components; impedances (as has been mentioned); noise rejection; cable type; sensitivity to cable differences, ground loop susceptibility, and, basically, the fundamental operating principles of the two kinds of interfaces.

One possible explanation that occurs to me, among many, and in addition to the ones Jon mentioned earlier, is that with the single-ended direct connection between the DAC and the power amp high frequency noise resulting from a ground loop between those two components may have been introduced into the output of the DAC, and found its way via parasitic circuit paths (such as stray capacitances, internal grounds, etc.) into the D/A circuit, contributing to jitter. In general, and depending on the specific designs, balanced interfaces will tend to be less susceptible to ground loop issues than unbalanced interfaces.

Regarding the broader question that is being discussed, my opinion is simply that where possible and practical PREFERENCE should be given to (a)keeping the signal path as simple as possible; and (b)replacing a component that is perceived as being colored or inaccurate, rather than introducing additional colorations or inaccuracies that are perceived as being complementary. At the same time, though, it seems clear that doing so is often neither possible nor practical.

11-29-15: Swampwalker

+1 :-)

Best regards,
-- Al

Well put Al, you have missed your vocation, your a peacemaker.

That last paragraph clearly and concisely hits it on the head.

Cheers George 

Al's last sentence is what really sums it up. Keeping it simple is the desired path( I agree) until you reach a point where  "simpler" is no longer the best sounding option. You have to be practical, listen and decide. It does no good to say direct source is better if it doesn't provide the best sound in a given system or circumstance. In this case simplicity isn't the best option if it fails to deliver the best sound for a particular listener.
Yes, Al, sometimes being practical seems to be the only way to go.  
It's not unlike adding the DEQX with its inherent coloration/distortion in the signal path of your system. Well, it's either that or change the room. For me,  I love my source too much to change it and for you,  you love your room too much to change it too.  :)
Regards. J.
That's a good observation regarding Al's system choices. When all is said and done, we're all just after the best sound we can get given the available options we have.  We all travel our own individual pathways to reach an objective/goal.
George, thank you kindly :-)

Jon & Charles, well said, and we’re all in agreement.  Just for the record, though, the DEQX in my system **is** the preamp (as well as the DAC).  Although others sometimes choose to use a DEQX in series with a separate preamp, and of course that’s fine too, if it works for them.

Best regards,
-- Al
Thank you kindly too.

I have been following your experience with the DEQX on another thread and it seems like a lot of hard work to get things going.

A lot of times, while we ruminate over components, we forget that the room is indeed part of the system and influences the overall sound in a very substantial way. Those who choose not to add the DEQX in the signal path may opt for passive room treatments and such like. 

I am quite lucky to have a room that synergises well with the rest of my system but it did take me a number of changes in configuration over several years to finally get it right. Certainly, what may sound good in my listening environment may sound wanting in another. That is why bringing home an audio component for audition in your system in your listening environment may produce results that are quite different, which could be better or worse, than at the dealer's showroom. An audio component brought home is like a box of chocolates....... :)

Charles1dad is on the money and has some very valid points. For people that go to live music gigs will understand the massive advantages of a good quality active tube or hybrid pre-amp. As well as some very good and accurate points from Charles, the biggest benefit is the music comes "alive". The performers become real compared to the cardboard cutouts they appear when going direct. Dimensionality, soundstaging, realism, and the emotion and passion of music all happen which gets you closer to the real thing, with a quality pre-amp into quality equipment compared to going direct which sounds dull, flat and lifeless.

A good quality pre-amp certainly brings the sound closer to the thousands of live music gigs I've experienced.

Also Power Amps will introduce their own colour? into the sound.

You summarized very well the point I hoped to get across. The  "alive" emotionally engaging aspect of music reproduction is a must have for my listening pleasure. Without this aspect the music sounds diluted, canned and less involving. For those who'd say these aspects are simply colorations added to the signal,  why does their presence increase the live, full bodied and realistic sound?  Anyway I long ago decided to choose what sounds more natural and alive to me. I can't/won't declare for other listeners any proclamation of what's right or wrong, these are clearly individual choices. The high quality active preamp gets it done for me( very often too much vital musical information is missing in their absence ).