I have an SVT-4 with an 810E cabinet. I run it mono out with a Speakon speaker cable. I use an Ibanez 405 5 string with active pick ups. This amp has worked great till recently. My band took aout 4 weeks off. While we were not playing I had the head in my home "collecting dust". It wasn't dropped or anything like that. When I got back in for the first practice I hooked up. I turned on the head and the input/mute light came on and I got no sound. I swithed the mute on and off with no change. I checked all of my connections on the back as well as the switches and everything was right. I changed instrument cables and even tried another guitar. None of this helped. I even tried swithing the EQ off and on. The light stayed on even with the gain turned all the way down and no cable plugged to the input jack. After about 3 minutes the sound came on and operation resumed as normal. Over the next 5 minutes or so the input/mute light slowly faded off and it resumed normal operation as well. Now my amp does this every time I use it. Also, the line out is affected as well. No signal out until sound resumes from the speaker cabinet. What gives???