YikES! You went DEEP there Mr. P !
I did that in the '94, and took 4 days to re-assemble ( I put every screw back in the empty hole as I dis-assemble). And shoot snappics GALORE.
Perhaps get a phase inversion amplifier. Real-time processing would do it, but integrating the stereo INTO it would be necessary, to not cancel the tunes too.
Someone else might know more-so how to do this...
edit:
and then, maybe not...
Good explanation
here, although ambient (non-music signal) noise, is not addressed