About that OD-1 circuit again: capacitor.

In the op-amp based circuit that constitutes the OD1 drive, there is a feedback capacitor.

The value is rather high: if I recall, 270 pF or around there.

That rolls off the high end quite a bit.

If you look at similar overdrive circuits, you often see smaller caps like 100 pF.

Anyone experimented with a smaller cap value in there?

All your signal goes through there, dirty or clean.