At $900 used in a manageable sized room like yours, for HT only use, I would definitely buy a more current single, large sub.
IMHO, a pair of M&K (or any other brand of) subs might make sense for a dual use system where twin subs can be used to smooth bass response without adding EQ, which some people find objectionable for a music system. For HT only, I'd use a single large unit and also make sure that I had Digital Room Correction capability (e.g. Audyssey) somewhere in the chain to achieve smooth bass response via EQ.
Just MHO.
Good Luck
Marty
IMHO, a pair of M&K (or any other brand of) subs might make sense for a dual use system where twin subs can be used to smooth bass response without adding EQ, which some people find objectionable for a music system. For HT only, I'd use a single large unit and also make sure that I had Digital Room Correction capability (e.g. Audyssey) somewhere in the chain to achieve smooth bass response via EQ.
Just MHO.
Good Luck
Marty