I had a problem with the volume dropping off and sounding fuzzy after 20 minutes or so. Alto Music's tech/repair guy checked it and said it was fine. I brought it home and within half an hour it happened again. So of course I scoured the discussions on these pages and someone, I can't remember who or where, suggested making sure the tubes are set firmly in place. I turned off the amp, unplugged it and opened the back and pushed the tubes in and haven't had a problem since. If and when I find out who suggested the fix I will thank him. A funny story: When I brought the amp back to be checked, I left the repair area and went to the amp section of the store. I found one of the guys that I deal with regularly and asked him if he would let me set up my amp and cab to hear that it was okay. While he is setting me up I ask him if he is familiar with the DT50. He looked at it and said "Too many knobs". I replied " too many knobs? just look at it like two amps, on on the left and one on the right". I told him to get a guitar and play it. He told me he had a Fender, a Blues Deluxe I think. I told him that I had one and sold it because I thought it was a one trick pony. He kind of agreed. You had to see his face when he started playing the DT50. I set it to English Crunch and asked him to back off the volume on his strat and he bagan playing some bluesy chords. Then I told him to turn the guitar's volume up slowly. He did that and was very impressed. When I was leaving I heard him talking about the amp with another guy.