personally, i wouldn't bother. it sounds great stock.
but if you really want to, check the datasheet of the opamp first just to be sure. i can't rightly recall what's in the crunch box, but if it's an RC4558, i wouldn't be confident with pumping more than 15V through it.
i don't know, the hassle and potential risks doesn't seem worth the possible supposed "improvement" in tone.