matchless and vox are commonly reffered to class A designs, but are less so in actual operation... There are alot less class A amps out there then you would imagine... even though some botique builders may insist otherwise..
IMO design class has less effect on the sound then overall design... what gives matchless and vox thier sound may be more related to the EF-86 preamp tubes and the tone stack...
like stephen said; check out aikenamps for more info...
Edit - here is a quote from aiken amps artilce on class a:
Quote:
Which is better, class A or class AB?
From a guitar amplification standpoint, neither class of operation is necessarily better, they are just different. You shouldn't get too hung up on the "class A" designation, because most of the push-pull amplifiers that are supposed to be class A aren't really class A at all, they are just cathode-biased, non-negative feedback class AB amplifiers. Operating class is not the reason for the tonal differences between these amplifiers.
The cathode biasing and lack of negative feedback is one of the main differences between the Vox clones and the Marshall/Fender style stuff. The typical Marshalls and Fenders used a fixed-bias output stage with negative feedback from the output back to the phase inverter input, while the Vox clones use a cathode-biased output stage and no global negative feedback. In addition, the output tubes and preamp stage/phase inverter configurations contribute greatly to the tonal signature of these amplifiers.
Edit 2 - here is a nother terrific bit of wisdom thanks to aiken:
Quote:
Which one to buy?
The bottom line is this: don't worry about whether an amp is "class A" or not. If you are interested in details, find out if it is cathode-biased or fixed-biased, and whether is uses global negative feedback or not, whether it uses a pentode, triode, or ultralinear output stage, and what type of output tubes are used. These parameters will give an idea of the "feel" of the amp, but in the end, you still must play the amp and use your ears to tell you which one is best suited for your playing style. Don't make a decision based on technical specs alone, you may miss out on a great-sounding amplifier!