I don't think Hsu is interested in making a single "killer" sub, they have been headed in a more modular approach to subs for awhile, what with the turbo, mid-bass module, and their promotion of the ULS as a multiple sub system ie the dual drive and quad drive. That philosophy may continue if they re-release their TN1220 like they have been talking about for a little while now, as that definitely had a modular aspect to it. It's too bad that they get overlooked for some of the monster subs out there, like the PB13, Submersive, etc. Multiple sub systems have some real and major advantages over single subs, even at an equal price, it's just a more sensible solution for so many more situations.