The MV uses a 220k resistor in series with the master volum wiper after the tonestack so u don't lose bass at low vokumes.. you gain bottom and bass at the expense of volume loss, but the volume is much more than the 1.2v P-P needed intomthe power section tomdrive it to full volume, so no real loss and benefit at low volume. Its an old MOD n covered in Kevin O'Connor's books.
As indicated above, it's still best when turned up. All amps break up as gain and vokume are turned up and signals clipped. To get a 100 watter to break up on the output, u'r gonna need to turn it up n it's gonna be brutally loud. Therefore, the amp you use should be scaled to suit u. If ur gonna play stadiums or outside, 100 watter is whatnu want. If ur only using for studio n bedroom, 1 to 5 watts is better. If ur playing clubs n using a PA to mic the cab, 18 to 50 watts is there u want to be.
The amp should be scaled to suit ur needs ultimately.