Dual Subwoofer Question

Several technical issues could arise
Can they both x-over at same frequency?
Do they both have full adjustability on phase?
Do they both have same x-over slope?

Assumming answers to all of above are yes, then IMO, its possible, but unlikely that it would be successful. First of all, I assume you would be using one for each channel, which would make balancing the system very difficult. If each sub has different room modes (likely if different sizes), you could end up with double the number of peaks. OTOH, in the unlikely possibility that they have opposite modes, you could eliminate peaks. HIghly to extremely unlikely, but possible. Audition before you buy, for sure. The only scenario where I could conceive that it has a reasonable chance of being successful is if you used the smaller sub to supplment the L&R and the larger for the LFE channel. You would probably need to set your processor for large L&Rs, and take a high level signal from the speaker outs of your amp, and then high pass that to the L&Rs.

Good points, ET. I have been thinking that with 2 subs, they would be run as monos. As many have found, there is some differential (stereo) information at these low freq and with two diff subs with two diff settings, x-overs, slopes, etc., I can see problems for music but probably not for HT. It is true that the two could make the bass more even, cover up for anamolies in the other, but if I was buying a stereo pair then I would buy a stereo pair. You would not use 2 diff speakers for L & R for full range or monitors. If you have access to a second at no cost, give it a whirl for sure, but if you have to buy the 2nd, why not get a matching sub.