Ok here's my dilemma, quite odd actually. I play through an ampeg svp-pro and a mackie 1400 poweramp. At a gig last Saturday, I wanted to go to the Mixing board, but the XLR on the ampeg is too quiet. Anyone know to remedy this? Regardless, I didn't want my bass to go direct to the board because i like the EQ on the preamp, so i plugged an XLR into the THRU Jack on the mackie. The problem is, when i did this, the Ampeg was constanly stuck on MUTE. I tried unplugging the footswitch, and using the buttons on the preamp, but the only thing that would get me working again was to unplug the XLR from the mackie, and then the ampeg worked fine. Does anybody out there have any idea why this would happen? My guesses involve grounding, or shorting, but i really don't know why plugging an XLR into a thru jack on the mackie would make the MUTE switch on the ampeg constantly engage. Any help would be appreciated. Thanks Brian.