I currently have a Sony SAWM-40 and want to replace it with either a VTF-2 or even better, SVS 25-31. ALso, my current HK AVP1/Technics decoder is dated and no 5.1 input for my JVC 723 DVD-A player. I've been looking at the HK SIg 2.0 specials around and like what I see. For all about the same cost (~$500) What's my best option (right now) to see the most improvement? New sub or better preamp? I have a HK 5800 along with Def Tech BP 30's...thanks!