Sub<$400

[morrewine]

Room 17'longX13'Wide

Harmon Kardon AVR 520
Cs2 Center
M60 Main
M50 Rear

Looking for a sub for under $400 must be less than 15" tall X 17" wide.

Thanks in advance.
Morrewine

[gregure]

Well, it doesn't quite fit your parameters, but the SVS PB 10 ISD is simply the best subwoofer in that price range hands down.
It costs $430, or about $480 shipped, so if you're willing to go a bit higher in price for a huge jump in performance, I would wholly recommend that unit.
It's a little bigger than your size limitations too, at 19" tall, but only 15" wide, then about 23" deep. It's a biggun, but again, you will never regret the aesthetic/financial sacrifices once you fire up Master and Commander or Return of the King. You will trully hear bass you never knew was there. Can't recommend it enough, and anything else in that price range is a piece of shit next to the SVS.
Hope I don't come off as biased.
Check out this link (http://www.hometheaterhifi.com/volume_11_4/svs-pb10-subwoofer-10-2004.html) for further reading.
Happy hunting.