The Hifi Trajectory Of Class D Amplifiers

Atmasphere, Bass amps were and often are made as cheap, crude implementation of class D, where you can get a lot of power in inexpensive portable package. Because of that many think of class D only as a crude inexpensive way to get lots of power. I'm not sure why you even brought the case of 500W class D not being able to keep up with 400W tube amp, since it is irrelevant to our discussion and refers to particular design and the way power was specified (only 6.7% difference in perceived loudness between 400W and 500W). In addition, in last decades bass amplification in larger venues got into PA system, making raw power of the bass amp relevant only for small theaters. Class D can be designed with any headroom, often has line and load regulated power supply, that doesn't sag under big loads and soft clipping similar to tube amps (whole Icepower family). In contrast, class A SS amps have very limited headroom, mostly unregulated power supply and hard clipping, but they are great example why suitability of given amp class for bass head says absolutely nothing about sound quality in home stereo system.

My Class D amps at home are top notch.

At the gym, they use inexpensive pro Crown Class D amps with large horn loaded speakers and instructors use their Apple devices as source. Not audiophile material in there with lots of echo and speakers in corners near ceiling but gets the job done nicely.

Very versatile technology!

In terms of sound good Class D amps I have heard and good tube amp setups I have heard differ not just in components used end to end but soundwise as well. Tube amps often provide some degree of warmth through the midrange. Class D amps I have heard deliver more of a "liquid" midrange but not warm at all. You have to add that somewhere else if warmth is what you seek. A good matching tube pre-amp does nicely.

I have one mostly digital (with phono and line level analog inputs plus various digital) integrated amp (Bel Canto C5i) and my main rig with BC CLass D amps and ARC tube pre-amp. They are both excellent performers but have their sonic differences, mainly the touch of warmth the ARC preamp delivers. I can listen to either happily for hours.

Mapman, there are some highly praised class D bass heads (like Ampeg micro or Gens-Benz Shuttle series) and some really bad ones, like with anything else.

To me liquid midrange of class D, that you mentioned, is closer to tube amp than SS amp sound. Other than that my class D amp is pretty neutral sounding. You like a little bit of warmth, that tube preamp gives you and I get the same from my warm sounding speakers. Either way, Icepower is a very good amp, for the money.

Class D progress, in my opinion, is related more to switching speed of output Mosfets that would allow to lessen phase shift by extending audio bandwidth. Companies like Fairchild or International Rectifiers announce new faster, higher power Mosfets every year. That is bottleneck IMHO. Everything else is only matter of integration level. It is also worth mentioning that modern class D modulator is not a simple ramp and comparator but resembles more Delta Sigma A/D converter. In fact PWM is a byproduct of Delta Sigma conversion, that appears alone as SACD. SACD is pretty much class D output (PWM) at high carrier frequency (2.8MHz) before filtering.

Kijanki, agree.

Neutral liquid midrange is a good thing.

I have insufficient data points to say all class d sounds that way but ice power does seem to.