For music the Rythmik is probably your best choice, but that model might be a little under-powered for your space. The HSU is probably the best "bang for the buck" in terms of power and output.
I have owned subs from all three companies and (in my opinion) Rythmik and SVS are better made and better controlled than HSU products, but HSU may have upped their game since I owned one. The last HSU sub I owned was a VTF-3 MK3. I haven't owned any of their sealed subs. I hear good things about the ULS-15. I know a lot of people like them.
I think you'd be better off with two subs, or increasing your budget and getting a sub that has enough output to provide more headroom in a room that size. Another brand to look at is Power Sound Audio, their owner came out of SVS and they make good subs and offer a 60 day trial period.
I have owned subs from all three companies and (in my opinion) Rythmik and SVS are better made and better controlled than HSU products, but HSU may have upped their game since I owned one. The last HSU sub I owned was a VTF-3 MK3. I haven't owned any of their sealed subs. I hear good things about the ULS-15. I know a lot of people like them.
I think you'd be better off with two subs, or increasing your budget and getting a sub that has enough output to provide more headroom in a room that size. Another brand to look at is Power Sound Audio, their owner came out of SVS and they make good subs and offer a 60 day trial period.