My budget is $600-700. My system is used primarily for SACD/DVD-A playback (80/20). I’m considering replacing my Velo CHT-12 with a SVS PB1-ISD. Currently for SACD/DVD-A playback I run my sub dialed down to 40Hz because my mains (set to large in 2900) cover very well down to 35Hz. Or, I’m considering buying a used 3 channel 120-200w amp (Adcom or Parasound) to run my front sound stage and move my H/K PA2000 to my rears. Where would I get the most bang for the buck? My modest 5.1 setup: Toshiba 35" h/k AVR 525 (ctr&rears) h/k PA2000 (L&R) Denon DVD-2900 JBL S310-II's JBL S-Center II JBL S36-II's (rears) Velodyne CHT-12 23'x18'x14' LxWxH (vaulted) Living room.