A great article on Class D/switching amps

Chris, you asked a great question, so let me answer it in three ways:

1) As a reference point I'm not a fan of amps like Krell or Halcro or speakers like Wilson because I find them to have certain qualities (details, dynamics, transparency) but for me I found them "sterile/cold" sounding which I do believe has much to do with their way of presenting timbres and harmonics in their overall sonic presentation.

2) Another example would be the Pass Labs X series, that I found quite dynamic, detailed, with great extension, but not very "musical" to my ears. However, when Nelson Pass came out with the XA and X.5 series, it kept the dynamics but also returned the timbres/harmonics of his Aleph design.

3) So, when I have listened to a few of the switching/D amps they offer great clarity, dynamics, and a silky presentation, but not the realistic timbres I hear in the best of class A linear amps.

I believe that many of the class D amps are very good bargains for their price range, but do not yet compete with the reference class a/b amps quite yet in their development. I'm quite aware that at this level of gear we are really talking about personnal taste and system synergy, so there is no "right" or "wrong" answer to what are the best amps or designs in the world.

I think the latest issue of TAS has a good summary of prevalent opinions on class D amps and why they differ.

Thus far I have heard some class D amps that I find sound good and some that I don't. I have had no opportunity to compare these with other linear amps. I owned some class D amps in the past and not been very impressed. The ICE modules, however, seem to be a substantial improvement.

Teajay,
Usually I agree with you, but not this time...
You apparently did not audition any new Krell amp(Evolution One, Evolution 402, 600 or 900) because they simply do not have anything similar to Halcro's(DM88,DM78 or DM38). If fact if Halcro is flavor #1 then new Krell's are definitely #2! New Krell amps use zero global feedback with just 8db of local nested feedback. Of course I am biased since I own one of them, but your description is section 1) is IMHO not accurate. Even A.H.Cordesman liked them in his review(BTW, he is known Pass fan!)...

Now back to original subject, class D are still not at the best level IMHO. I audition only two of them in my home(Jeff Rowland Model 501 and Audio Research 150.2) and both were nearly not as good as current SOTA tube or solid state amps IMO. Jeff Rowland Model 501/Concerto Pre combo were better then ARC 150.2 is every way, but they could not stand against my reference amps in any way. As I said before bass was very good and tight in Model 501. Midrange is pretty good, but somehow artificial to my ears and highs... High Frequency needs little bit more in-depth description, low highs are very open and almost bright sounding, but upper highs are closed-in or non existant! Exactely as J.Valin described in his review, they are cut off. Soundstage size is just decent and depth is a big problem in both Model 501 and specially in 150.2, depth impression is pretty limited with both of them to my ears.
To be absolutely fair I must say that Model 501 needs to be compared to tube or solid state amps up to $10k IMO. So, my comparison is not very valid to most people...
Also, when you buy Pass, Krell, Boulder, ARC, CJ, CAT, Lamm etc. you get the design and long time work of N.Pass, Dan D'Agostino, Jeff Nelson, Ken Stevens, Bill Conrad/Lew Johnson, Vladimir Lamm etc. In class D amps you get B&0, Tripath etc. modules implemented by some "desingers" in different metal(or not) boxes. These days great name like Jeff Rowland is simply putting somebody else designes in his excellent metal boxes. Also 99% of class D amps use switch power suplly. Good or not? Only time will tell...
Limited bandwith(mostly 5hz-60khz)... Since class D natur is limited bandwith, is it also a limiting factor soundwise in class D amps? Big damping factor(usually above 500)... It also impact pretty much on class D amps sound IMO.
Do all class D amps sound the same? Based on my limited experience(only two models) I think not, but they all share some things(strange timbar IMHO and soundstage depth shortage).
"I believe that many of the class D amps are very good bargains for their price range, but do not yet compete with the reference class a/b amps quite yet in their development. I'm quite aware that at this level of gear we are really talking about personnal taste and system synergy, so there is no "right" or "wrong" answer to what are the best amps or designs in the world."
Here Teajay I full agree with you!

Down here where I live, the question of whether or not a Class D design is superior to $40,000 Class A amps is utterly academic. My RWA Signature 30 is the best sounding amplifier I can afford and it outperforms anything I'm aware of at less than 3 times its price.
The mere fact that we are discussing subtle areas of comparison between the newcomer, dirt cheap digital amps and the finest, most expensive conventional designs speaks very well of the future of Class D.
In photography, we might find a parallel. I'm told by some hobbyists that film provides a certain character that digital doesn't quite convey but that digital has a clarity and precision that film was never able to capture.

And in doing such a comparison as the Ab. Sound did,most of the amps probably did ok to very good compared to how they set everything up.There is no haze or colorization to what i listen to.