Re: Dumb Marshall Question
The mains tranny is the power tranny...there are 2 styles an upright and a lay down, it's just the way they physically attached to the chassis.
As for an advantage to each I know of none however a large number of old and a number of historically amazing sounding Marshalls (some of Jimi's the EVH amp, etc) had lay down mains trannys...I have a storng feeling thats the big deal surrounding them.