A single VTF-15H isn't enough for a small room, now that's a bass head!
If you're looking to add a second subwoofer to your home theater then you can expect an additional 6 dB increase if you co-locate the two subwoofers, which will be a large upgrade.
If you have any additional questions, please feel free to contact us.
The Hsu Research Team
985 N. Shepard Street
Anaheim, CA 92806