Before you dump the subs you have remember how much placement and seating position affects subwoofer performance.
I wouldn't be surprised to find the HSUs outperform the DefTech subs (box size relative to woofer size seems to be a factor as well) but unless you have heard the two subs sitting in the same spot in the room keep in mind that the difference might not be as big as you think.
Having said that, I also think the VTF-3's are fantastic.
M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
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