The Class doesn't really matter, and most of the amps out there advertised as "Class A" such as the Vox AC30 are not really Class A. Its just a marketing term in most of those cases. Of a bigger importance to the difference in sound is the method of biasing, i.e. cathode or fixed bias, if there is negative feedback or not, and what the preamp and power amp voltages are. Sunn tube amps are fixed biased with lots of negative feedback, and are almost always ultralinear too. Personally, for guitar purposes instead of bass, I'd disconnect the negative feedback loop, change the preamp voltages, change the tone stack, and change the phase inverter design....but it would be easier just to use another amp, which is why I don't use Sunns for guitar. For bass I love them though!
Greg
