Receiver Output

[kevinokev]

A friend of mine is having trouble getting the same amount of volume through his front right speaker as the rest of the system.

I've tested his wires and also using a few different speakers, but each configuration still has the front right speaker much quieter than the rest of the system.

I thought this might have been a fade or eq problem, but the system has already be restored to it's default settings.

Any ideas as to why the one channel is outputting much lower than the rest ?
Sony STR-DE875