Well, I don't know what it takes to bypass the amp preamp stage. With 4CM the amp's EQ stack affects the sound, so it's still going through there. I've run the PG in 4CM with the FX loop on and off. Same thing.
I have an old Marshall CODE amp and I've run the Mains Out to the CODE's Aux input and that works, but I'd rather run the PG to a tube power amp. I just don't want to cause any damage to the Origin.
I'll try running the Mains Out to my amp's Return.....
What would be the difference between Line and Instrument on the Mains Out going to the amp Return?