Well its been almost a year since any kind of an upgrade and the withdrawls are setting in. I have been considering a new HSU sub. Currently I have an older Paradigm PS1000(about 9 years old) and have had no complaints, Its plenty loud enough but I wonder if a new HSU would improve my system "musically", or would it be diminishing returns. I have the M22's, vp150, and QS4's. Let me also say I have an older house with wooden floors, i.e., a bright room.