subwoofer question

Perrew,

No.
(Provided that the subs are crossed below app. 90hz.)

IME. YMMV.

Marty

Bob, Marty so if i hear you correctly youre saying there is no stereo info or localization info below 80-90Hz. So the superiority with two subs would be cancellations of node and downside if you take money into account would be you could buy a better single sub?

I've extensive experience with that subwoofer. On it's own, they are fast, accurate, musical, and dynamic. They are good subs overall, yes. You can, however, bottom them out/distort them with strong movie material. That is the downside to any of those MX series, accept the MX5000! That's the truth. That said, two of them, will likely ameliorate that potential issue, help cancel out any distortion between them in mono operation, provide more efficiency into your system(regardless of how you configure them), and more output for sure. However, as far as volume of your room goes, really, one should be enough for that small space. Infact, I wouldn't even mess with two of thoose in that room, I think it's a space killer - unless you can get real creative. It's doable, but usually cramping your space.
For the money, at $900 for the pair, that is a a good deal, as things go. You won't get hurt, and can sell em later, and get the money back.
I would be looking for a simplified solution, myself. Even though you can do more with multiple subs, I'd simplify and EQ in that room. I would NOT be looking for subs placed around the room, in that limited space. Balance is important here, as always.
I would probably say, buy the deal, and see if you can get by with one of them. You may find that one sub is all you need. Place it up front next to your center channel/mains, and be done with it! It will integrate well, have proper phase for all seats, and perform well in that room, with a good EQ integrated into the system/processor.
I guess I'm saying that, if I was in your shoes, yes, I'd go try the M&K's, and see what you think. You'll only ,likely get less accurate bass potential from other choices, and they're easily sold if if you change options later.
This way you'll know what the M&K's are capable of in your room, in your system. Then you can try others later if you want.
Yeah, I'd try em. M&K makes a good overall product, that's very durable too.

Perrew,

I've done a/b comparisons with my old Velodyne subs wired for stereo then re-wired for mono. At 100hz, I wasn't sure that I could tell the difference between mono and stereo. At 80hz, I was sure that I could not tell the difference. At 125hz, I thought that I could and at 150hz, I was sure that I could hear a difference.

FWIW and, as always, YMMV.

Marty