Class A vs. AB vs. D... can you hear a difference?

I sold a lot of Primare in the past. These days I seldom sell
it. They went from class AB to D. When you compare the old
one with the new, the old ones are more musical and even have
a better 3 Dimensional stage. The Pioneer receivers in class
D sound like shit.

But class D is great for subwoofer amps, and even in some amp
it can be good.

Pass class AB amps sounds great in class A and B.

Having heard a fair sample of all three, in general I would say yes, each group tends to have some similar sonic characteristics as a group that will still vary somewhat in comparison case by case.

Class A is more towards a warmer tube amp sound than A/B. Sound is still more damped however.

Class D also is more towards tube amp sound in the sense of being more liquid in the midrange in particular. Sound is very highly damped but more holographic and neutral to colder sounding in particular than most Class A/B.

Class A/B can vary widely all over the place but tends to be more towards the middle of the others sonic traits in general.

General guidelines on a topic such as this has too many variables to offer any useful info. IMHO. I have heard Class A, AB, B, all sound great and terrible. Same for tubes in A, A-AB, etc. Most important is how the amp matches the speakers. PT

Had an 1980s vintage Yamaha CA-1010 Integrated amp for a year, just sold it. 18/18 watts class A then to 90/90 watts class AB. Could not hear "switching" and setting output to "A/AB" sounded better than "AB". More detail/more solid lows. Not a major difference, but surely noticeable.

My experience is limited to an A/B and five switching amplifiers including a Pioneer receiver. Overwhelmingly the switching amps didn't become congested when driven hard and were consistently less fatiguing. After repeated comparisons I concluded they're presentations were simply different and I enjoyed them both.

My class D performance improved greatly with upgraded AC (not conditioned) and attention to cabling synergy, something many detractors fail to confront.

The Pioneer receiver's two prong AC improved the most with my homes AC upgrade. In the two channel system the receiver held its own very well with the mono blocks. And like the monos it likes lots of copper strapped to its terminals. I settled on NuForce speaker cable.

Blanket statements regarding switching amplification are a dime a dozen often made without any set up details. Class D is not plug and play and simply another amplifier choice.