Tubes/SS Power Amps?

I've only heard, auditioned, listened to top of the line tube amps; consequently, I don't know squat about top of the line SS power amps. My problem is "heat". If the SS gets hot, I might as well have tubes.

Reviews that I've read on top of the line SS amps, always mention the heat. Rather than have a SS furnace in my listening room, I'll go with tubes. By the way, I don't think there's much difference between tubes and SS amps when you have a tube pre; especially top of the line. I'm searching for an amp in the vicinity of 100 watts per channel with balanced inputs, preferably mono blocks. Cool running SS is what I'm looking for. Can you help?
Orpheus, I must jump in to disabuse you for writing that "I don't think there's much difference between tubes and SS amps when you have a tube pre; especially top of the line."

There are dozens of threads on the Forum which speak to the issue of amp/speaker electrical compatibility. I suggest that you read Ralph Atmasphere) Karsten's White Paper that discusses the so called Voltage and Power Paradigms. Search ther Forum archives to find it.

Here's another great site that also explains why some speakers are tube friendly and others not:

If one is a serious audiophile, IME/IMO, I think the issue of amp type and heat pales when considering amp/speaker electrical compatibility.


Compared to the tube amps that I've owned, ALL SS amps run cooler, even the Class A amps. :)
Not monoblocks, but I'm using a Cary 200.2 s/s amp with an ARC Pre, and it sounds very nice. Might be more power than you're looking for, but no heat to speak of at all. A/B design, has both Balanced and RCA Load is a pair of Martin Logan Theos.
I also think your statement that a tube pre gives you the real tube sound and magic is wrong.Tube power amps make an enormous contribution to the character of the sound. I can't tell you how much it changed my system. I had tried using tube pre amps but they simply don't come close to what tube power sounds like.
There is this fantasy that a tube somewhere in the chain will give you tube sound. If that is true what about the converese, does SS anywhere in the system give you the SS sound? Will an SS pre and tube power sound like SS?
I agree with mechans. Tube pre alone cannot give you the liquidity that a tube pre n tube power combination provides. It's like a teaser only and leaves you wanting more. Just like oliver twist said: sir may I have more????

I'm going to give you the advice that, I'm sure, many other readers of this thread are thinking of:

If you want tube flavored sound without the heat of tubes and class A ss amps, you should try out a quality tubed preamp of your choice with a class D ss amp or monoblocs. You didn't mention your budget or other components but here are some good class D amps that may give you what you're searching for:

Acoustic Imagery Atsah monoblocs

Mola-Mola monoblocs

Merrill Audio Veritas monoblocs

All 3 incorporate the latest technology in class D technology, the Hypex Ncore NC1200 switching amp modules. All 3 of these amps have high power capabilities, are generally neutral in sonic nature,run at about room temperature and I think they all are about $10-12,000/pair. Although they each utilize the same Hypex modules, they all also use proprietary methods in their surrounding designs. I've recently become a class D fan after pairing my mid-level tubed preamp with a budget ClassD Audio stereo amp. My amp is not in the same league as the monoblocs I suggested above but I am still more than thrilled with mine, anyway. You should probably give atleast one of these amps a tryout in your system prior to purchasing another amp, IMO. If your speakers require a high powered amp(s), I would even say it's a must audition.

Good luck on your search,
Hi I had a similar need as yours...less heat (upstairs in texas get's hot fast)...but I always owned tube amps...ARC or BAT...A few years ago I bought a pair of Ayre MXRs.

Really happy. They get very warm to the touch...but don't really emit the shelf above them is just barely warm...

Not sure your price range...The new Ayre VX5 might be a great choice to...

When there were such places as "High end emporiums", I spent so much time in those places, that my wife swore I was seeing another woman; she couldn't believe that I was obsessed with "high end sound". This was at the same time I began to subscribe to "Stereophile". After reading "Recommended components", I would go to the salon and audition whatever they had, this way I learned to classify sound by "A", "B", or "C". The SS amps were affordable class "C", while the tube amps were class "A" and "B"; consequently, I never heard a Class "A" SS amp.

In case no one has noticed, our summers are getting hotter, and AC bills are getting higher. If I'm going to have a furnace in my listening room, it certainly wont be a SS furnace. All the SS amps I've owned ran cool, but I never owned a Class "A" SS amp, and from what I've read in the reviews, "they all run hot", and that's the problem. Does anyone know of a Class "A" SS that doesn't run hot. Here is a list of Class "A" SS amps: Bryston, Classe, darTZeel, Halcro, Jeff Rowland, Lamm, Pass Labs, Musical Fidelity, and of course there are many other high quality SS amps. In regard to the "stereotypical" tube, SS comments, that's the way it was, and not necessarily the way it is. ARC sounds awfully SS to me, and CJ has changed from the way the used to sound, to a sound closer to ARC.

Jfrech, the Ayre VX-5 looks absolutely stunning, A Herron at about the same price is on my audition list; thanks for the "heads up".
I agree with Mechan's post. Tubed amps do indeed make a difference that IME cannot be duplicated with a tubed preamp. However, it is my experience that really good SS gear can also sound like music. My Class A Clayton amps have a low bias switch so I can warm them up in anticipation of playing them hours later, or even play them at low bias if I am not seriously listening. They are very musical and fully balanced (as well as 300wpc all in Class A). I suspect there are at least a few other musical SS amps out there. One I always wanted to hear (but haven't) is the Jones audio amp, based on the review at the 10Audio site, although I don't believe they are balanced.
I agree with those above who think that, even with a tubed preamp, a tubed power amp makes a necessary contribution. That said, we don’t all hear, process and evaluate music the same. If the differences between SS and tubes aren’t discernible to you (which is fine - it doesn’t mean that you can’t hear, it just means that you don’t care) then by all means, unless you’re seeking a substitute for logs burning in a fireplace, buy SS. Get a relatively efficient A/AB design; but even then, your speaker’s demand for power will be a big factor, so choose an amplifier that easily provides for those demands.
You didn't mention a price point so it's impossible to give you an intelligent answer . I had a fire at my beach house last fall do to my faulty tube amps , so tubes are now out of the question , for me .
The tube amps were almost new and were made by one of the oldest manufacturers around , they did quite allot of damage to the house which is still not inhibitable . I'm hoping the place will be ready for use by mid summer .
I no it's rare , but it's something to ponder .
Orpheeus10, You mentioned the system by which stereophile rates and then puts amplifiers into classes. Just for clarity, these were the amplifier classifications I was talking about.

Conduction angle classes
Class A
100% of the input signal is used (conduction angle Θ = 360°. The active element remains conducting[6] all of the time.
Class B
50% of the input signal is used (Θ = 180°); the active element carries current half of each cycle, and is turned off for the other half.
Class AB
Class AB is intermediate between class A and B, the two active elements conduct more than half of the time
Class C
Less than 50% of the input signal is used (conduction angle Θ < 180°).
A "Class D" amplifier uses some form of pulse-width modulation to control the output devices; the conduction angle of each device is no longer related directly to the input signal but instead varies in pulse width. These are sometimes called "digital" amplifiers because the output device is switched fully on or off, and not carrying current proportional to the signal amplitude.

The above is sourced from Wikipedia.
Phaelon, I'm well aware of what you were speaking of and class AB probably sounds as good as A, and runs much cooler. Class A is too extreme as far as heat is concerned, and I wouldn't have one. After all is said and done I'll probably end up with tubes, but as I stated before, I've never even heard a top of the line SS amp.
Orpheus10- I think Phaelon is on to something. Perhaps you have Class A operation confused w Sterephile Quality ratings? All Class A operation amps run hot because their active elements (read transistors) are carrying current all of the time. The heat from Class AB amps vary, as they can be designed (biased) to run more in Class A or to switch to Class B sooner. Not all excellent SS Class AB amps run hot. For example, the McCormack amps I owned all never got more than warm. McCormack amps modified by Steve's SMcAudio are outstanding amps if you want to get something that runs cool. A cooler running tube option would be one of the ZOTL amps from David Berning. Or consider higher eff speakers that can be run w "smaller" tube amps like the RAM RM-10.
Guys, I appreciate that Orpheus asked about SS/tube amps and raised a specific concern about heat. I think many of the posts above are excellent and responsive.

However, it's unclear whether Orpheus has considered electrical compatibility with his speakers. Not sure that Orpheus mentioned what his speakers are. Look . . . I own ARC tube gear. I love it. Put tractor tracks and a cannon on the gear and you'll have a tank -- for me, 4 tanks.

Even still, the articles I cited above do a great job explaining electrical compatibility issues with tube and SS amps. In fact, the issue is even more subtle because if a speaker was designed and voiced to be driven by one type of amp versus the other, matching the wrong amp can affect the acoustic presentation.

I'm done harping. I just think electrical compatibility is the first thing to get out of the way.

I'm sure you've heard about the generally different distortion characteristics between tube and solid state amplifiers. I find the difference quite dramatic and I'm driving my tube amplifiers with a solid state preamplifier.

If it's simply a matter of heat, Carver tube amplifiers power tubes actually run cool to the touch. My plasma display puts out much more heat than the Carvers.
Heat schmeat. Tubes are more fun.
See if you can audition Ayre MX-Rs paired with a Nagra PL-L or Jazz and then form your own opinion.

I noticed that no one responded to my mention of Stereophile's ratings of equipment by Class "A", "B", and "C". First and foremost, I am not pushing the magazine; however, I subscribed for years, and during that time I went to high end emporiums to evaluate the magazines rating system, as well as the equipment.

For the years I was able to do this, I discovered their ratings to be quite accurate. Occasionally, a component would fluctuate from "B" to "C". This happened with the CJ PV10, and the Grado Sonata; however, I don't recall any component dropping out of Class "A". It was for certain that if any component fluctuated like that, it was a best buy.

Small manufactures complained about not getting their products reviewed, but if you think about it, the magazine also had a reputation to maintain in regard to volume, and consistency of product.

I no longer subscribe to the magazine because the equipment was completely out of my price range; however, I still use old magazines to make decisions. What was your experience in regard to the magazine and it's rating system.
Orpheus, let me address a specific brand you mentioned - Herron.

I've attended the CES in Vegas for at least 15 years, although not the past two. Through that time I developed a very high regard for Keith's products since his room always impressed me as one of the most musical and enjoyable at any given year's show. Previously he utilized other name brand speakers but more recently he brought a prototype pair of his own design.

While not wanting to enter the debate on how much a tube preamp/line stage can influence the sound, I will say his line stage was tube based while his amps were SS monoblocs. The result was musical, without edge or distortion, dynamic, and could be listened to for extended periods without any fatigue.

Given your objectives, I wouldn't make a purchase without auditioning Herron.
I don't think that too many would disagree that through time as equipment has improved, there is less of a line between the very best tubes vs ss. I'm sure we have all heard terrific systems from both camps. I have heard great systems with all kinds of variations. As Tim suggested above (Noble100). I would chime in to say that very good class D amps, as mentioned or if on a tighter budget the new m amps from wired would be terrific with a good tubed pre amp. I am also fond of the newer Coda amps with a good tubed pre, I've heard very musical combinations there.
Good Luck,
04-15-13: Timlub
I am also fond of the newer Coda amps with a good tubed pre, I've heard very musical combinations there.

I am fond of the older Coda amps with a good tubed preamp. :)
LOL...Jmc...I think the same....I have a mixed system...for about 3-6 months (winter) I use my Modwright 9.0 tube pre into my B&K 200..Summer listening goes to my Coda CSi Integrated that gives me the sweetness as well...Happy with my Coda and Tube/SS combo for the seasons..Coda throws off some heat but not as much as two units combined.
@Shakedown, I'm running a Cary SLP-98P F1 with a Coda Model 11 amp (100 wpc pure Class A). The 15.0 might be about the closest current offering to the 11.
So "heat schmeat" was an insufficient response? And here I was trying to be succinct.

I will never forget one of my most enjoyable afternoons at a high end emporium. It was late October and a bit chilly in the small auditioning theater, when a customer came in requesting a big CJ tube amp. That amp put out as much heat as a small fireplace.

The customer was a fireman, and it just so happened that we liked the same music. While listening to the sounds of jazz, we discussed our preferences in amps. He liked the warm sound of CJ, and ARC was my favorite. This was at a time when those two amps were as different as night and day. While ARC is pretty much the same, CJ had what was called the "CJ glow"; it really did something special with jazz and horns, as he went on to explain.

There's no better way to spend an afternoon than discussing the merits of your favorite tube amp, while listening to jazz on high end equipment. Heat was a good thing on that day
Orpheus10, there are other threads out there for what people think of reviewers. Check out:

When a Reviewer "likes" something and What reviews do you trust if any?

Personally, I don't get much out of reviews or ratings. The rating system basically says the more expensive a component is the better it sounds. I always loved it when Stereophile would rate some gear that I liked poorly, because then it would become much more affordable. :)
Regarding Stereophile magazine... I dumped that magazine years ago when it went overly political and vulgar. Using curse words in reviews and making public policy/political commentary in an audio review magazine was crazy. The writing was pedantic, arrogant and smacked of young pseudo-intellectual drivel. So... unless it has changed (and perhaps it has)... that magazine is something I will stay away from. That said, their subjective rankings, while of course being incomplete (limited basically only to those products whose manufacturers advertise with them) were seemingly reasonably accurate as far as I was able to tell.
Orpheus10, there are inexpensive ways of dealing with heat. You don't need air conditioning for starters, if you do it right.

Now if you set up your system according to how much heat it makes, don't expect it to sound like music. If it does, great, a happy coincidence.

Hot transistor amps are hot because they employ a greater amount of A operation in their output- this is to improve linearity. The same is true of tubes, but they are inherently more linear in many cases.

One thing is certain- all the solid state embodiments known so far make more odd ordered harmonic distortion than their tube counterparts. Odd ordered harmonics in trace amounts are easily detected by the human ear, which recognizes them as brightness and harshness.

So you might look into the idea of creating ventilation in your room to get rid of heat without air conditioning. I have seen this done quite successfully, such that you could sit in the same room with 2 class A 500 watt triode monoblocks all day and all night without getting uncomfortable, and without air conditioning.
Atmasphere, I had an SS amp that began to run hot, so I put a fan on it. The hotter it got, the better it sounded. I put two fans on it, next it caught fire taking two new woofers with it. That was the first and only amp I've ever owned that caught fire. I thought that was just supposed to happen to tube amps.

If creating ventilation can work, that's what I'll do.
Orpheus10, amps in general are not supposed to catch fire :), tube or solid state.

Sounds like that SS amp was overbiased and went into thermal runaway.

The way to do the ventilation is to put one are two vents over the space that the amp/amps will occupy. You can get flexible ductwork inexpensively that can then be routed to the outdoors by a small squirrel cage fan. If you do it right, it will be quite unobtrusive. If you live in a northern climate, you may have to take some simple steps to prevent the ducts from being a heat loss in the winter.

This approach is cheaper, quieter and more reliable than air conditioning.

I'd be very interested in hearing your thoughts on class D amplification. Have you heard any of the newer class D amps in a good system? How do you think this new technology will affect the tube based amplifier business?

I find it ironic, as others have pointed out on other posts, that the original and oldest hi-fidelity technology (tubes) pairs so well with the latest and newest technology (class D).

I was thinking you could embrace this new technology by doing one or both of the following:

1. Offer a tube preamp that is specically designed for use with class d amplifiers.

2. Offer an Atmasphere class d amp, based on the Hypex Ncore 1200 or possibly the Pascal amp modules, to complement your current and future offerings. You could also use your proprietary designs around these class d modules.

I know a class d amp with a tube input stage/power supply, designed by and sold through Atmasphere, would create a big buzz in the audio world and with your potential customers. I will definitely voluonteer to test out anything you would decide to build.

Basically, seeing you post just got me thinking of possibilities. I'm just very interested in the new class d happenings and thinking out loud. But, in any case, I wish you and your company the best.

We've been looking at class D for 9 years now. We have certainly thought about it.

The preamps we make now would work fine with any Class D amp.

The concerns we have had are: is class D a threat to our tube technology? Answer, yes, although not with any current embodiments. However Class D is the rising star in amplifier technology and if its still early on the price/performance curves it may yield something yet.

Second, should we be building one? Answer, maybe. It could well be poor marketing on our part to not have a class D amp in our lineup, as we have been focused on getting as close to sounding like real music as possible. So far that has been easier with tubes, but I am pragmatic enough to know that that could change!
Before I became an "audiophile", as opposed to someone who just listened to music, I was an electronics technician, and my belief was, "If you can't measure it, you can't hear it, and the best specifications sound the best". After I got into the "high end", I discovered I could hear many things that can not be measured. At the same time I discovered that what sounds best "theoretically", actually sounds the best for real. Theoretically, class A tubes sound the best, and most audiophiles will agree on that.

Atmasphere, could you compare Class D, with Class A tubes theoretically?
Orpheus10, why in your opinion do Class A tube amps "theoretically" sound better than Class A solid state amps? Do tubes measure better than solid state devices?
Based on observations/listening experiences to date, I'm finding good Class D seems to sound more like good tube amps I have heard than most other SS amp technology. Plus they have the ability to drive many difficult load speakers out there today that tube amps are more challenged to do, without great cost, expense, size and heat.

Based on listening alone, I find my Class D amps, Bel Canto ref1000m monoblocks, hard to fault in any real way. But on paper, the very highest frequencies that might be heard are the area where Class D historically may not be up to snuff with the very best amps otherwise. That technical bottleneck as I understand it is due mostly to switching frequency limit and effects on associated low pass filtering needed. The latest Class D amp modules I read about seem to indicate that switching frequency continues to increase and improve as the needed technology improves. That would seem to push what is possible even higher.

Practically, I think Class D has arrived not just as being viable but the most practical approach to high performance amp design. Technically, the frontier is still moving with Class D technology it would seem, much as it is still with computers and related digital technologies.

The sky is probably the limit down the road, to the extent that it matters practically. Practically, what it means is though performance will continue to go up, becoming even more practical for even the most demanding applications, even more importantly, cost/prices will continue to go down as top performing Class D technology becomes more mainstream for high end audio applications.

Outside of high end audio, where Class D appears to already have a firm foothold, Class D seems to have already clearly arrived and is starting to take over.

Mapman, transistors switch on and off, as opposed to always on as is the case of Class A tubes. AB amps have two halves of a cycle that match. "Audibly", these three can sound so close to the same when the best parts are used, that "most" people can't tell the difference.

In motion pictures, what in reality is many still frames becomes a "moving picture". This analogy of still frames is good for transistors, digital, and switching amps, which is why extreme audiophiles preferred class A tubes. While none of us can detect still frames at a movie, "some" audiophiles seem to be able to tell the difference between switching and non switching amps.

It's for certain I can not instantly tell the difference when comparing "high quality" amps with different designs; but for me, I've found it to be cost effective to follow in the footsteps of "extreme audiophiles" who can; and that's where the critical decision making process comes in.
When I first heard the Bel Canto ref1000m monoblocks in my system as a replacement for Musical Fidelity A3CR amp that ran largely Class A I believe, the sound was stunningly different in every way. PErhaps the single biggest difference I have ever heard switching components. IT was like a simulated reproduction of the music had been replaced with something much more resembling the real thing. I thought the bass was gone at first until I was able to get tuned back in. Then it was there in spades and way more dimensional, articulate and controlled than ever, which seemed to enable all the rest to be revealed much better than before as well. It seemed like a thick layer of distortion that existed prior was removed. I did not know what to make of it at first, but I quickly realized I could now turn the volume up much louder than prior without any discomfort or fatigue, and the music just seemed to continue to expand naturally rather than making me want to stop. One of my more shocking audiophile moments for sure.

Driving my tube amp is one of the places where it really differs from SS amps I've gets rounder with a still listenable tone at highish levels, and that works for me sub is SS though, and it just has to be turned down to compensate, as I'm not insane. Or maybe I am.
Orpheus10, just FWIW if you think we can't see the frame rate at a movie theatre, go see the Hobbit and then go see the HFR (High Frame Rate) version of it!

One thing that Class A tubes have over Class D is bandwidth. How about full power -1/2db at 150KHz, only 2 db down at 300KHz? Some might argue that class D (and for that matter, traditional transistor technology) have more current (and they would be right) but the question is 'Is that important?'

The correct answer is no. High current ability is not particularly important. Why? First, look at the specs of any transistor amp, any class D amp, in particular the distortion spec into 4 ohms. You will see that the distortion is higher into 4 ohms than it is into 8 or 16 (likely the 16 ohm distortion will not be spec'ced, but it is lower...).

To put this more clearly, if you want to have the system to sound smoother and more detailed, even if you have solid state, that will be easier if you are driving a higher impedance. This is because that increased distortion (driving lower impedances) will mask detail and come off as brightness. This is the difference between a good hifi and a music system that sounds like real music- the lack of electronic artifact.

Now, on top of that, about 50 years ago tubes were being declared obsolete, much like vinyl LPs were in the 1980s. The fact that tubes are still very much a part of the audio marketplace is not some sort of fluke- they are still here because they are still popular half a century on. This is the more telling fact actually. If tubes were really obsolete they would have been gone decades ago. In fact these days its easier to find old tubes than it is to find old obsolete semiconductors...
Mapman, normally, the cost and weight of an amp that generates that much power, is prohibitive. Since I've never auditioned such a powerful amp, I have no way of evaluating the effect of that much power on the audio; I'm sure it was quite different.

My best audiophile moments are with 2 track reel to reel. While I thought they made all recordings better, they make bad recordings worse; but in the case of good CD's or LP's, the playback is always better than the original source. "Better" does not mean different, but bigger, and in the case of CD's they sound more like audiophile LP's. I imagine this might be the same effect as a more powerful amp. The reel causes the sound stage to fill the room more completely with the same amp.

500 watts into 8 ohms for a 19 lb amp is unbelievable. There are so many factors involving a class D amp that make them worth considering, and if I ever have a desire for power hungry speakers, I'll know which amp to choose.
If you consider NAIM amps as good and if the rest of their gear is the same as my 5i - then they run very cool

My 5i is on 24/345 (vacations) an never gets warm
- Except in winter when my hands are cold :-)

A few gotchyas...
- naim recommends only their speaker cables (see website)
- they only have RCA and DIN inputs
- they work really well with NAIM power supplies - go figure
- sources should be grounded otherwise they may hum

Other than that they are detailed, articulate, dynamic and sound great

They are a lifestyle choice - that sound great :-)

I'm using a lower cost class D amp ($630 ClassD Audio SDS440sc stereo amp rated at 440 watts@4ohms) than you are using but I still notice the same attributes that you described.
When I turn up the volume the sound retains it's balance and there is no compression, clipping or tonal changes. The music just gets louder while exhibiting an effortless quality.

But, what's even more interesting and impressive to me, is that it has this character when turning the volume down, as well. I enjoy this amp, whether with music or ht, much more than my previous amp (Aragon4004 that had similar power but was a class A/B type). I never heard, or at least noticed, any other amplifier type that has such good performance at both low and high volume levels.

I am definitely not implying that tube amplification is obsolete. Class D amps, imho, do not sound the same as good tubed amps. There will probably always be users that continue to prefer the virtues of good tube sound, myself included. I've achieved some of the tube sound I prefer by combining a tubed preamp in front of the class D amp.

Class D is so neutral, quiet and clean that I'm probably hearing the sound of my preamp and source more than the sound imparted by my amp. I have noticed an improvovent in sound (more tube like) with the VTL/ClassD Audio combo than my previous VTL/Aragon combo. This was further improved when I recently replaced my preamp's NOS Mullards with a fresh set.

Lastly, I just want to mention the improved bass performance of class D in the bass area of my system's performance. The Aragon had good bass with my inefficient Magnepan 2.7qr spkrs. But I felt the need for more bass and added a subwoofer crossed over at 45hz. When I substituted the CDA for the Aragon, I immediately noticed a slight overemphasis in the low bass region. I turned down the sub's high cut flter down from 45hz to 35 hz and this corrected the issue. I think the class D amp's high Damping Factor (in the thousnds) was the cause of this.

This little CDA amp took control of my spkr's woofer panels like the Aragon was never able to, even though it's 1/3rd the size, weight and price of the Aragon. There wasn't just more bass, the bass was tauter, more textured and more nuanced. I confirmed this by turning my sub off for a few days and didn't really miss it that much. I would loved to have used, or at least tried, a tube amp but my spkrs need too much power to use for both music and ht.

I would think the traditional high end solid-state companies should be more concerned with the improvements in class D technology than the traditional high end tube companies. This is probably reflected in the number of ss companies vs tube companies offering class D amps. On the ss side, Mark Levinson, Rowland, Bel Canto(started as a tube amp maker yrs ago) and, I believe, Cary all have introduced class D amps. The only tube company I'm aware of that currently offers class D amps is ARC. I'm sure others know of a few more on both sides. I was just reading that PS Audio is about to introduce a new class D amp this year, too.

As Mapman and others have pointed out on previous threads, there are a slew of new companies that are just beginning their journeys to possibly becoming traditional high end companies utilizing the new class D technology; W4S, Merrill Audio, Mola-Mola, Acoustic Imagery, PS Audio, etc.

I'm sure there will be more companies jumping on the bandwagon.

IMHO, class D just has too much going for it (good and improving sound quality, small size and weight, very efficient, very powerful, relatively low cost, cool running, neutral sound character) for it not to be the wave of the future. I really do hope you decide to jump on this juggernaut bandwagon while there's still some room on it.

Best wishes,
I'm of the "first watt" school...if an amp is well designed and used properly it can sound amazing, regardless of the wattage, cost, or type. Speaker impedance matching is key of course, and if you expect to fill a gigantic room to sweaty disco levels with a 2 watt amp, you shouldn't be here. Good tube amps generally aren't breaking a sweat at strong listening levels, and I agree with Atmasphere about classic design service issues...where was I supposed to get IBGT transistors for my trusty old Forte' 55? (I was never 100% sure what transistors were in that thing anyway)

Wolf_Garcia, while I agree with you and Atmasphere, because that's as far as my current knowledge will go; I have to take what others have written in regard to Class D amps, into consideration before the hot Summer months.

Noble100, "Class D is so neutral, quiet and clean that I'm probably hearing the sound of my preamp and source more than the sound imparted by my amp. I have noticed an improvovent in sound (more tube like) with the VTL/ClassD Audio combo than my previous VTL/Aragon combo. This was further improved when I recently replaced my preamp's NOS Mullards with a fresh set."

What Noble100 has described, is just what the doctor ordered; cool running, imparts the sound of an excellent "tube" pre with no sound of it's own. This is definitely something I could live with for the summer. As much as I love my tube mono blocks, I can live without a lit fireplace in my listening room during July.

Enjoy the music.
"Class D is so neutral, quiet and clean that I'm probably hearing the sound of my preamp and source more than the sound imparted by my amp."

That's a good point and may well be the case. I use a tube pre-amp with my Class D amps as well (Audio Research sp16).
Are Class D amps less expensive to make? Seems like they are (more power for the buck). I used a great little Class D Ampeg bass amp recently, and it was amazing. I still think tubes are more engaging (and suit my low threshold of gear entertainment) especially from an esthetic point of view, and I dig the tweek factor (who "rolls" parts of a Class D module? rhetorical question..)...a Class D hifi amp would have to have blue VU meters and an Art Deco case for me to warm up to it, but that bass amp was sweet.
"a Class D hifi amp would have to have blue VU meters and an Art Deco case for me to warm up to it,"

That would be cool. Any Mac Class Ds yet? That would get my attention.

GIve it time....
"a Class D hifi amp would have to have blue VU meters and an Art Deco case for me to warm up to it,”

...and maybe a couple of very low wattage lightbulbs protruding from the top :-)
Now yer talkin'.