A few months ago I picked up my new Hartke HA5500 and 2 Hydrive 1x12 cabs. I've been really happy with the rig for tone. However, I'm getting buzzes and hums when using the XLR out. In a live setting, I get a big crack when I turn the amp off and then a constant buzz in the PA when it is off. When recording, there's an underlying hum on the signal even when my bass level is 0 and my amp is powerd on or off. The only thing that stops it in either case is removing the power chord from the amp. Here's some trouble shooting I've tried with no success: -Ground lift switch -Unplugged my bass while amp is on to make sure it's not the instrument -A different XLR cable (different ones were used between live and recording) -Making sure the amp is on a separate breaker from stage lights/computers and other possible electronic interference. Any other thoughts for troubleshooting?