Ideas?   Putting system back together. I can get Turntable, CD player to work through 
left and right channel.   When switching back to
video (comcast) I can only get center channel. To work. To clarify.   Center channel is powered by Arcam unit.  Left and Right are switched over to my Conrad Johnson pre and power. All worked before taking some components out. Thinking I may have messed up w a setting on 
Arcam but no tinkering is getting me back to 
where I was.   If anyone has any suggestions-they would be most appreciated.   
What input on the CJ pre-amp are you using to connect the L&R front pre-outs from the Arcam AVR into pre-amp? If the CJ pre-amp has an HT bypass/processor loop, make sure you have selected that input (as suggested by @noromance ). If you are using some other input, insure you have selected the correct input.