Very much depends on the circuit: You could alter the headroom of some circuits by using a voltage doubler to run them at 18v, reduce the gain of the input stage, or have an input level trimmer: This last suggestion is pretty much the same as "turn the (guitar/bass) volume pot down a hair".
I know the last one, already used it but as a gain control on the acapulco gold. Tried it on a misbehaving chorus and nothing but thats a fault on my side. However I do see some compressors that use that method.
Which chorus? Something like the little angel uses an opamp input stage to give a x2 gain boost: Hot pick-ups could clip this, so your options would be to replace the series input resistor with a resistor + pot so you can adjust the input gain (e.g. 470k + 1M pot to allow gain to be variable from x2 boost to x 0.666 attenuation).