I am using the 4 cable method, using my marshalls for most of my tone & the helix for effects, (an old jmp 50 watt & a jcm 900) We hooked up the 900 & everything worked as it should, I thought the 50 watt would sound better for the venue we were playing,, Here is where the problem happened, The send & return from the helix got hooked up to the speaker outputs on the marshall & the cabinets got plugged into the effects send/return of the marshall, After that I lost the mono/left output on the Helix. Just a little bit of sound with the helix volume cranked, ,, I plugged into the 1 below (Right) & I have Normal output. Is there enough voltage from the speaker out to have fried the output On the Helix, Any suggestions,, I have been using line 6 for years & the Helix is By far the coolest Unit I have had,,, Would now Be hard to do gigs with out it,,,