Hi, i have an existing Marantz SR5500 receiver but i still want better stereo sound while im listening to music. what should i do? do i have to buy a separate power amp or integrated amp? my speakers are rated 150W at 8ohms. how much wattage of amp should i add-on?

another question. while listening to stereo music? which receiver input is best to use? is it the digital input (coax/optical) or the stereo (L/R) analog inputs?

final question...what is bi-amping? how is the connection configuration for this set up?