I'm not a fan of MP3 for critical listening ... or for much casual listening, for that matter. I do have my 'Puter network's A/V capabilities linked to my main AV system, however, and to the master bedroom's somewhat less ambitious AV system. As for inputs and outputs, here's the back panel of my Yamaha. All of the digital I/Os are independently assignable, and all functions can be renamed in respect to what is displayed on the unit's front panel display, the TV screen, and the remote's display. Still, there isn't an open interface available. I find need for outboard switching. And for several hundred dollars worth of interconnects ... you oughtta see the snakepit of wires behind the thing.