Passive pre-amps have definitely made my system sound worse. Using no pre-amp with my CD playe, tuner, and even XM Polk radio was worse, and that is far from great anyway. A far as the electronics and physics involved, please inform me. I am curious. I can understand the tuners, because a switch bypasses the probably crappy gain control, and I can understand that my electronics could be better than the passive pre-amps I tried, but no pre-amp with the CD player?
