I have $600 to spend on a subwoofer for a room about 16' x 16'. I will be using my system primarily for music. I've read some reviews of both HSU and SV Subwoofers but I can't decide exactly which model. A review I read on this forum comparing the PB1 and STF3 indicates the SVS unit would be a better choice, but where does the VTF-2 fit in there? It's $100 cheaper. I need some help deciding between the PB1-ISD, STF-3, and VTF-2. I don't really want a cylinder, due to space concerns.