Ian,

The ZP100 has analog audio inputs, line outputs and speaker outputs.

The ZP80 has analog audio inputs and line outputs, plus optical and coaxial digital outputs.

If you set the ZP100 for variable volume control, both line and speaker outputs are controlled simultaneously. I don't think there's any way to control them seperately.

The Audio Input is for a line level device (CD player, TV, etc.) I don't know how feedback could be avoided, as there's no logical link between inputs and outputs.

You might want to consider a ZP80 to connect to the F80 digitally (much better fidelity), but, of course, you'd lose the amp from the ZP100.

Good luck,

John

Main system: Cable, Apple TV, HD621, G68D, AC11, 218, DSP7200SE (L+R), DSP3200 (L+R Rear)
2nd system: Cable, Apple TV, MC200, HD621, 568.2, M3100 (L+R)