I have tried out the REL T-9 in my system, and while it melded well with my Von Schweikert VR-5 HSE speakers and sounded quite good, it didn't have that really low depth to it that I wanted for live rock recordings and HD TV movies.
While I was saving up for a sub, I came across some very convincing reviews on the Hsu subs. the VTF-3 MK5 HP and VTF-15 H Mk2 really piqued my interest, but they did not meet up with the all-important WAF (Wife Approval Factor -- they were too big). Thus, I will be auditioning and writing a review of the Hsu ULS-15 Mk 2 very soon that, according to Hsu's site, are the most musical subs in their line.
Cheers,
Juan C. Ayllon
Ayllon Media