Class A/B switching cause sonic problems?

From experience I agree with Mike Creek in that an amp that has class A drivers with class AB outputs is certainly a legitimate design topology. I've used more than one solid state amp product that works this way & they sound just fine to me, and I am quite particular about sound quality. Of course a pure class A design is going to have a more purified sound than the hybrid design, but the tradeoff is a lot of wasted electricity & a hotter listening room. This extra heat isn't really an issue during cooler seasons, but on warmer days you'll certainly notice higher AC bills &/or a hotter house. Simply let your ears decide which you most prefer.
The amp doesn't normally "switch" back & forth though, this is simply driven by the input signal level exciting whichever stages at any given moment in time. One exception is the old Carver commutating power supply, but I wouldn't recommend that deisgn for any critical-quality applications.
Switching power supplies might be found in either type of design, & yes they can be noisy (although more efficient). In a properly designed component, either linear or switching power supply could sound equally good. I believe that Meitner, Rowland, & more recently TACT have manufactured examples of properly designed & executed "switchers".

Hi Bob. I guess I'm not totally clear on A/B amps. So you're saying the amp will switch even even I kept volume levels low so not to go above 1 watt output on the power amp? Aren't these amps supposed to put out class "A" for the first watt? Then "B" after that?
There don't seem to be any class "A" amps available anymore that I know of so maybe the market has decided for me what I want. But I do know ATC does use class "A" amps in their active speakers.
Thanks evryone for the help.

I can answer it as well.
1 watt of output power is measured according to a certain freequency probably 1000Hz. If it goes to the bass freequencies it would anyway switch since higher current is drown onto the load greatly increasing a slew ratio...
There are A/B amps where the switch to B occurs arround 25...30W where you normally listen to them in class A.

Douglas Self's "Audio Amplifier Design Handbook" 2nd ed. covers it well.

Cdc- There are many class A amps available, though probably more tubes than ss versions. There is a theoretical advantage to class A amplification, but there is the efficiency issue. In class A/B amps, all voltage and driver stages (that I'm aware of) are class A. It's only the output stage that is configured for class A/B. There are amps with higher biased class A/B output stages that run up to 15% of their output power in class A; the brand Symphonic Line comes to mind.

Obviously, if you need lots of power, class A/B amps will likely be necessary because of the efficiency. However, for absolute sonic reproduction with the fewest compromises, class A operation is usually first choice.
Remember, class of operation alone won't make up for compromises in the quality of parts used to implement the circuit design. There are some excellent examples of good sounding amps in either class of operation, though to my ear they are usually tube units.

Some of the newer, true digital amps, (Tact, PS Audio, etc) use a completely different class of operation. They are extremely efficient, and have garnered some very high praise sonically speaking. I've yet to hear them for myself, but that is another option for you to consider if you need high power.

As for switcher power supplies, lets not forget about one of the truly innovative engineers in audio, David Berning, and his designs. Bob_b has already stated the facts concerning this power supply type. As Ezmeralda11 has pointed out, if you're really interested in learning the technical info of different amp circuit topologies, there are several good books on the subject.
Enjoy.