Longest length for interconnects

[robmack]

Hi,

I purchased a new Yamaha HTR6063 receiver and am deciding on how I will configure Zone 2. There are two possible Zone 2 connection configurations -- line level stereo output to an external amplifier or speaker level outputs to speakers.

I'd like to recycle a stereo preamp/amp that I have in storage rather than use the Zone 2 amp in the Yamaha.

What is the longest run of interconnect that I can use between the Yamaha receiver and a stereo preamp before signal degradation becomes an issue? The stereo preamp/amp will be aproximately 20-25 meters from the receiver.

TIA,
Robert.