What will raising the Va of atransformers provide?

Larger transformers should be able to handle current swings better and have a higher capability but may not necessarly sound better in every case. It is all in the excution of the design. Avil-Lindburg [sp?] are the ones I used when I had some custom designs made up years ago; they are excellent and were used by Mark Levinson in some of their amps. Large and expensive then, I suppose they are more so if still avalable.

Because Class A runs at full output all the time while AB varies with demand. Since the transformers already handle full output bigger ones will not improve the sound. An insight into why well designed Class A amps are so large and expensive.

Dcarol, why do you think it does not? A true chass A amp draws 4 watts ALL THE TIME for each watt of output. So a 100 watt a channel amp will draw a constant 800 watts from the wall. An AB amp idles at a few watts and rarely draws its maximum current. Therefore the transformers in an A amp have to be up to ALWAYS supplying full current as opposed to doing it once in a great while. It is obvious that class A amps require more robust parts to deal with the constant heat generated; they actually run cooler at full output than at idle. Class A amps never see a sharp increase in current draw because they are already drawing their maximum; how then would bigger transformers improve the performance? Yes you could increase the power rating but that would mean everything else would have to be bigger also. I thought the origional question was just changing the transformer and I have seen nothing in what you said to convince me that it would.

I might add that I was one of the origional Krell dealers and have also sold Class A amps from Musical Fidelity and Stax. I had a preamp with a custom power supply using 2 Avil Lindberg torrodial transformers and very large caps built in the early 80s; my ASR Basis phono stage uses a 50 lb power supply and my MF Kw line stage weighs 50 lb or so and will put out 50 volts. I also use an aftermarket PS for my MF V-DAC. I am well aware of the importance of power supplies; my point was that JUST the subistution of bigger transformers in a design that already had adquate ones was not a guarentee of better sound. As Atmasphere points out it is a lot more complicated than just making a simple subistution.