This is a bit vague, but I am asking about ways to get a crossover that will relieve the speakers of bass (high pass filter) as well as the corresponding roll-off of the sub (low pass filter).
You are going to ask if this is a PC based system, or a traditional stereo, etc. I am interested in knowing any way you can skin this cat. This is more for future ideas than solving a specific situation in front of me (though I know AfterLife can use a good solution for PC).
Also, I have a vintage amp that has separate pre-out and amp-in connections. Is there a practical way to add a line-level XO and split the signal to the sub? (also, Blues Doctor is in this situation with his Yamaha R-S700)