At was one of my requirments: one knob for volume, one for sub adjustment.
The units remote volume control is linkable with phone splitters. So I have a total of 4 cl-rlc's: 3 are used for standard volume adjustment, and are linked together to one knob, and the 4th is used as a sub level control. I keep the computer volume at max and adjst the level of the rlc's to taste.
Though i feel that I must mention that I am having problems with one of the units not working all the time-it seems that I have a one defective one
Edit: for clarification, I only have a 3 way setup- tweeter, mid, and sub. But you should still be able to use a similar setup in a 2,3,4,5, or whatever setup because the units are linkable