Was playing for about a half hour in 50 watt mode, Master @ 50% when the output just faded out. No other noise associated with the dropout, just went silent. Switched the standby on to off to see if that would fix it. No go. Next with standby off I turned master volume down then switched from 50 watt mode to 25 watt mode and turned the volume up to 50% and output was back to normal. So I switched back to 50 watt mode and all was ok.
My rig was set up just taking the guitar and going into the front high input with a DT25 Cab. Anyone else have this behavior?
Added: This is a sort of journal about my experience with the DT50HD/DT25 Ext. Cab. & HD500.