In reply to:

Actually, I was thinking a resistor that you could take in and out of the system, maybe a variable one (varistor??) since resistors are used as high pass crossovers. But I'm just making this up...



Uh, caps are high pass crossovers - resistors (like the ones Axiom grudgingly send out to people who think their speakers are too bright) just reduce the signal to those drivers.

Bren R.