Subwoofer for music only ?

 For a room that size you could not do better than an REL T/7x, Even the T/5x would perform spectacularly for virtually any type of music you like to listen to. You will also discover there is no concern regarding matching with virtually any brand of satellite. speakers you own

If you are not familiar with these spectacular subs, I suggest checking out their website and even discuss you needs with a factory specialist. This is one audio product you would not likely trade for anything else. REL is also a wonderful company to help with optimizing your setup, which is surprisingly simple. The price/performance ratio is pretty much off the charts

AXPERT

@pennfootball71 - Isn't that expected or is there a specific reason that you think that a T7 is superior to the T5 for the OPs situation?

@elliottbnewcombjr - Can you explain more about bass becoming directional due to overtones as it relates to subwoofers?  I'm sure that there's some disagreement over the frequency where sound is no longer directional, but for the sake of discussion let's say that it's 80 hz.  If the low pass filter is set to 80 hz, then any overtones that are above that frequency would only be heard through the main speakers maintaining the directional aspect of the sound.  This is why it's so important for a subwoofer to blend seamlessly into the main speakers.

@mceljo Perceptively, a single sub is localizable even at 80 hz. Typically, you won't localize anything up to 120ish hz with 2 subs on the front stage. You may not localize anything with 4 subs probably even up to 150ish hz( 2 on front stage, 2 along side walls, etc depending on room layout).... Perceptively (you may need to experiment with it)...the more the number of subs, the higher up in crossover you could 'get away' with.....

@mceljo it has a bigger nicer cabinet and a 10 inch passive radiator instead of an 8 inch passive radiator so it can dig lower and harder