RC 50 output issue

[john floridis <john@johnfloridis.com>]

Does anyone know what might cause a slight distortion in an output  
signal, in this case from an RC 50, enough to be audible in a p.a.  
system, but NOT in the headphones of the RC 50.  All levels seem to be  
normal.  The output distortion is audible in both L and R channels  
when going to the PA.

This is an acoustic guitar going through several stages including a  
Fishman Blender, a POD X3 LIve, and a couple of small pedals to the  
Boss, so several opportunities for clipping, but I don't know why it  
would distort in the main outputs and not in the headphones.

I'm missing something obvious, yes?

John