Can I take the monitor out of the 370, into the guitar input of a second head, then speaker out of the second head to a cab? If so, what settings should I use on each head? Trying to test the preamp section of the 370 but don't have a powered speaker per the suggestion I read. I'm getting distortion at volumes >2 mainly on low and low-mid freqs. The distortion sounds like a rattling / blown speaker. Tested multiple cabs, Ampeg 410 HLF, TC RS212, Avatar TB153 that's not it. Any advise would be appreciated.