Put an Overdrive pedal in the mix and jump your channels together! That amps wants that combo! A Boss OD-1 if you can find it or a Tubescreamer, If you want the pedal that will make that amp sound like any baddass modded Marshall with out any mods get the Plexitube Tonebone by Radial.
Radial...
Try this!
Marshall Large Box Reproduction Head Cabinet [cab-mar-large-box-head] - $275.00 : The Vintage Sound, Your source for vintage tube amplifier and guitar parts!