I have them set up parallel using my Line 6 M5. Works decent except for adjusting tone and volume. I have them stacked so I can't access the controls on the bottom amp. Sooo... How can I run the amps together to be able to use the controls on the master amp to control the slave amp. Remember the MB 115's have two inputs, headphone jack, line in and XLR out. That's all. No effects loop(sucks) and no preamp out. While we are at it, could I hook yp my Ampeg BA 108 in this mess with it's effects loop to use it as a preamp for the other two? Please help!!