I think you can do better with HSU, SVS or maybe Monoprice Monolith.
In that price range you could get the PB or PC2000 from SVS and I think they'll outperform that T/9i. SVS make very good subs and are as audiophile quality as they come.
The PB-2000 Pro subwoofer features legendary SVS technology for immersive home theater experiences.
www.svsound.com
Cylinder subwoofer delivers massive output and subterranean deep bass extension while saving floorspace.
www.svsound.com
If you can bump the budget for something like that S/812 that opens a lot of doors, putting you into PB3000 territory. A pair if those would be plenty for your space and would loaf most of the time. Meaning they'd run effortless, smooth and cool, but be capable of delivering some serious bass when you want it.
Unrivaled subwoofer output and deep bass extension for the price with control, accuracy and refinement on par with subwoofers costing three times the price.
www.svsound.com
HSU offers a little more bang for your buck. I'd say the VTF-2 MK5 would be sufficient and either the VTF-3 MK5 or VTF-15H would be that little extra when you want to shake the walls. You know you want to...
The best value for price home theater systems and subwoofers on the market guaranteed
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The Monoliths have measured and reviewed here very well and are great choices too.
Monolith™ 12" THX® Certified Ultra Subwoofer The Monolith™ THX® Certified Ultra Subwoofer sets the standard for bass output, low dis
www.monoprice.com
And of course because I love overkill it's big brother...
All of those are great choices for music or home theater and would mostly come down to aesthetics and how big you want to go. You seem to have a decent budget. I really like the Monolith 15 and PB3000. A pair of either of those would really kill it, but you can probably get away with a pair the smaller ones I listed as well.