Dear Line6,                    My M13 has been part of my rig for well over a year now and within the first year it was replaced due to a faulty main board. I have been pretty satisfied with it up to this point other than the failure (which manifested itself as the "mysterious" power cycle problem). In any case you did replace it (which only took a month). The new unit operated without a hitch until tonight. I turned on my amp and was greeted with a hideous hum that is only present on the left/mono output jack. I am completely baffled.   I use the included standard power supply And always have. And I run through a Tripp-lite power conditioner.  I tried several different audio cables, stereo and mono. no change. I tried putting it into tuner mode, no change.  Power on, louder hum. Power off, quieter hum, but not by much.  I verified the integrity of the cords by going straight from guitar to amp. I tried it with a different amp on a different power circuit (at home). The only thing left is that there is a short somewhere.   I leave the cords plugged in most of the time because I play at a church and don't have much need to move it. I am reasonably sure the jacks are in near perfect condition. I do keep it secluded and out of the way of traffic so it doesn't get knocked around or stepped on (in an inappropriate manner anyway).   I was an early adopter and judging from the long chain of problems I would say this item is, in general, a LEMON.  So, Line 6, judging from the tremendous amount of activity regarding faults with the M13, do you plan on doing more than sending out the same questions over and over and over from Hugo and Renken or are you going to make some kind of gesture of good will here?   500$ isn't chump change to most of us working stiffs and I feel this needs to be treated with some extra care. Your customers deserve better than accusatory responses that basically end up calling them idiots.   Sincerely,  Christopher B.

Edit: I was looking at my previous post and it was about 10 months ago. That was how long I had my original M13 before it was warranty replaced.   :(

and an additional edit - video of the problem. http://www.youtube.com/watch?v=zbWcftO9-jw&feature=youtube_gdata_player