I had the same problem as well. I thought I had caused it as I had this amp on standby mode when I was changing one of the wall outlets to an audio grade one. I was too lazy and stupid so I didn't turn off the circuit first. I ended up tripping the circuit. Well, the amp started to hum on one side after I got everything hooked up.
I contacted Madrigal and they told me that I probably blew one of the caps. I sent the unit back for service under warranty, had to pay $120 to ship the beast to Madrigal, but they covered the return shipping. I guess they must have changed them to MIT caps. That was about 2 to 3 years ago, and I haven't had any problem with the amp since.
FrankC
I contacted Madrigal and they told me that I probably blew one of the caps. I sent the unit back for service under warranty, had to pay $120 to ship the beast to Madrigal, but they covered the return shipping. I guess they must have changed them to MIT caps. That was about 2 to 3 years ago, and I haven't had any problem with the amp since.
FrankC