Hi Jim,
I’m a firm believer that the best sound possible is done through an active set up. You send just what you want to the amp and driver it controls. You can make any speaker active by defeating the passive crossover and taking advantage of an active crossover such as a Mini DSP. Active means that the crossover is digital and before the amplification. The amp's full power is used just for the signal you send it rather than it getting choked by a passive crossover. You can create any slope, Q, and delay that you like with the easy straight forward Mini DSP software. There are FIR and IIR filters, you can read up in the advantages and disadvantages of each. I use a mini DSP in IIR processing at 56bit/96kHz and actively control 8 channels on my system. Upper/lower main left and right, Left/Right main sub, and two rear subs. Pairing this ability with Room EQ Wizard (REW)/Multi Sub Optimizer (MSO) you can get the best sound for multiple listening positions. Most room distortion is in the sub region due to the large standing waves (not much needs to be done above 80Hz). A few measurements in REW and fed into MSO let the computer crunch away and it delivers slope data that can be plugged into your active Mini DSP crossover. It will resolve time delay so the sound reaching your ear is what was recorded, manipulate phase to cancel unwanted waves at the listening position, and minimize distortion from your room which makes boomy unnatural base. When your room is measured in REW you can see what you hear. A sub array (4 or more) is really necessary to properly handle Sub EQ. REW even has a virtual room set up you can quickly build and it will tell help you see where best to place your speakers to do the least correction as others have spoken to here.
Follow the white rabbit. . .
-Steve
