Stack-in-a-box hi-gain mods:

This is old stuff. A simple grid-to-ground silicon diode clipper on the second tube stage is probably enough for "more distortion".

The PAIA Tubehead/SIAB family is designed to provide subtle real tube distortion. It doesn't provide "rock guitar solo" distortion. We can get a more distortion by overdriving the tube stages a little too much, or (better) by adding a second tube.

Of course we won't be getting "Power Tube" distortion, you'll need a power amp for that.

N.B. it ain't broke, it don't have enough 6-pole rotary switches.

References: