I believe that Hsu's STF subs are now made in China, which probably leads to the perception that they aren't made as well as the U.S.-made SVS subs. But, even there, all of the components inside of these subs are manufactured by outsource partners, some of which might be outside of the U.S.

The biggest issue with subwoofers is often the room integration, and the variable tuning profile on Hsu's subs can actually provide some benefit in this area because it changes the frequency response profile. But, whether or not you will benefit from the feature depends entirely on the room acoustics, your placement, and your listening position location. Rather than worry about Hsu vs. SVS, I would start looking at your room and assess potential acoustical problems that you need to remedy via room treatments and/or equalization.

Since you're asking about music-oriented subs, a lot of audiophiles prefer sealed designs, which neither Hsu nor SVS use. Most subwoofers on the market are ported because of their higher output. Companies that make sealed subs include B&W, Martin Logan, ACI, Vandersteen, Paradigm (their Servo line only), Sunfire, Atlantic Technology, Rocket, and Acoustic Visions. A general rule of thumb that I've seen tossed around is that if your room is small to medium sized, then you should consider a sealed sub, and if it's large (400 sq.ft.+), then you're better off with a ported sub.

This is because the room boundary will reinforce the lower frequencies. The smaller the room dimensions, the higher the frequency at which this reinforcement begins. Sealed subs have a more gradual dropoff at the low end, which matches the rate at which the room boundary reinforces the low frequencies. Ported subs have flatter frequency response down to the tuned port frequency, but their dropoff at the low end is much steeper. In a small room, this can create bass with an exaggerated boost in the low end and less extension than a sealed sub can deliver in that same room. In a large room, the sealed sub no longer benefits from the boundary reinforcement, and the higher and generally flatte (down to the tuned port frequency) output from a ported sub has a distinct advantage.

But, no matter which sub you opt for, you should get up to speed with learning how to measure the in-room response on the subwoofer, and how to adjust for room-induced interactions that can create huge peaks and dips in the frequency response. If you don't own one already, get a SPL meter at Radio Shack, and then get a CD wth test tones on it. Those will allow you to measure the actual output of a subwoofer, and identify any problem areas that your room has created.

Once you've identified the problem areas, then the next step is to make the room adjustments. This can be done with corner bass traps, repositioning the sub, changing the listening location, and/or equalizing the sub. In my room, I use a Behringer Feedback Destroyer as a parametric equalizer, and it has been absolutely vital to getting my subwoofer to sound right. IMO, correcting for the room acoustics makes a bigger difference in the quality of bass that you hear than which brand of subwoofer you go with.