I am in no way an expert on this, but here is some info:
From another forum I read:
"I find that for some odd reason the input to channel 3 shows up on 3 and 7.
After another go around last night I noticed that if I plugged in only channel 1 it copied to 4 until I plugged in a cable to channel 4. In the first case the plug on the cable in channel 7 wasn't fully seated. Not a bug, it's a feature. Now I remember reading about it in the owners manual, many years ago."
You can find the manual here:
http://www.geocities.com/keezamaaz/
I think the answer to your question is on page 5 under "Mixer connections"
Good luck!
