I have suffered the same thing. i powered line 6 m5 via Diago power outstation, daisy chain a few pedals as well. It work well for a few months then it went faulty and the pedal couldn't power up. Then i use the Genuine power adaptor, the pedal came back to life for awhile but DIE after a few month eventhrough i used the genuine power supply from Line 6 itself.
Question is Will 3rd party power supply(T rex, voodoo lab, Diago, 1spot) SPOIL line 6 pedal ?
Help please.