I use a HD 500X with a DT25 head. Has worked great for last 6 months but after a rehearsal at church it stopped responding right when we went onstage to play a second service. Everything lit up but no sound. Unplugged and powered up the 500x....nothing. I had to leave the stage and go turn the amp off and back on. The 500X finally worked. Just had a different band practice and same thing happened. The display started flashing different settings, volume got real low and then came back. I'm perplexed. Am I possibly switching too quickly on presets when trying to find the right one?