Goheelz,
The Panasonic amplifier sounds best when fed a digital signal, as it is able to amplify the signal directly without any D/A or A/D conversions. Adding a nicer disc player would add two conversions to the process: the digital to analog conversion in the player, then the analog to digital conversion in the Panasonic.
Bpfunk,
If you want to maximize your current investment, consider having the Panasonic SA-XR70 modified by The Bolder Cable Company. I replaced a Rogue 99 Magnum pre and Musical Fidelity A3.2cr power amplifier with a Bolder Cable modified Panasonic SA-XR45. The Panny embarrassed separates in virtually every area of critical listening.