Hsu or yamaha sub?

I've been looking for a reasonably priced sub to match with my Thiel CS.5's. I don't want to spend a lot of money, yet I don't want to sacrifice quality.
The VTF-2 and Yst-800 seem to be the two hot subs for $500 or less.
Has anyone matched these to a quality pair of speakers for a stereo setup? How did they sound? Any suggestions would be helpful.
I plan on connecting this sub to my preamp out on my Arcam Alpha9.
I would get the HSU. Another decent new under $500 subwoofer is the Monitor Audio ASW-110.

Used you might find a REL Q100E or Stratus II for a little over $500.

I have both a hsu and a yamaha. I don't have the yst800, but the reviews are really good on it. The yamahas I've heard indeed sound good. In the end, I would have to go with the Hsu subs. Really, really deep bass. The only fault I can really find is that they can be overdriven easily.Idon't think you could go wrong with either. Hope this Helps.
You cannot possibly go wrong with the hsu. I have used it favorably against subs three times the cost. I have not used the Yamaha, but I am sure you will like the Hsu. good luck.
Hello. I have never used the Yamaha YST-800 but I have used their older YST-500. I also have owned the HSU VTF-2. I personally liked the older YST-500 better than the HSU. I didn't really care for the HSU personally. I am not sure what all the clamor is about with this sub. If anyone thinks it competes against QUALITY subs costing 2-3 times more they are out of their minds. I tried for about 2-3weeks straight to get this grand performance out of the HSU and it just didn't happen. For me anyway. I think you should try the Yamaha YST-800. There seem to be a ton of HSU subs on the used market and you hardly ever see a YST-800. I wonder why?????? Oh yeah, the HSU is U-G-L-Y (IMHO)too.