Just getting started with my home theater/audio setup. After thoroughly perusing the various forums and reviews I determined that the Yamaha RX-V 2500 and a pair of Paradigm Sudio 20s (I ended up with the v2) would be the best starting system for under $1,000 (thanks to the Audioholics forums I got it done for less than $900). Althought I just got it set up a few days ago and it sounds great, I wouldn't mind a little more bass extension. Is it worth it to add a sub, and if so which one?