I know there are a lot of post on this topic, but it seems each one is a little different. Here is my issue: 1. With the instrument cable plugged in either channel, there is a significant 60Hz hum that increases with volume. 2. The hum changes when I thouch the chassis. It also changes if I wave my hand in the chassis (being sure not to touch anything). 3. The hum is very minimal without the instrument cable in 4. There is no hum in standby. 5. There is no hum when V1 tube is removed. 6. I have tried a different tube in V1 with no change. I really appreciate any insight into this issue!