Class A/B switching cause sonic problems?

It appears that you're mixing up two different topics. Switching, sometimes called digital, power supplies (recent JRDG, Chord and others) is completely different from the class A/B switching controversy. Regardless, the general consensus is that amplifier designs where both halves of the waveform are handled by a single device is preferred.

From all that I have read on this subject, my personal
opinion is that class A is sonically superior. Presently
I own a Bryston B-60R int. amp that I enjoy greatly, but,
I decided when funds become available I'll be going with a
Sugden A-21 Class A int. amp.(I've heard that amp w/Harbeth
HL-P3ES2 is a glorious match.) Bill

Onhwy61, for the amp to perform in different classes of operation the DC power on active elements must be distributed differently so that the offset voltage is "located" at the very "bottom" of input "family" characteristics of a transistor or valve. Thus the switch of the power supply also takes place.

In my point of view that it's great to have either class B or class A.
Class B claimed to have less harmonic distortions theoretically but for real there is no ideal offset point so the positive-wave element will be also passing negative that will be added thereafter to the negative element and vice versa; creating unneccessary phase shifts as well which won't be present in class A.
The only point in class B is its efficiency and ability to fit into the small budget amps.
A/B amps due to the DC supply switching sort-of combine both cons from A and from B.

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