My left 57 is making a sci-fi hissing oscillating noise when left on for a couple of hours. My good lady heard it the other night I shut it down,next morning everything peachy.



Came back from work system on for an hour and a half( on the cans but 57s fired up) thought the lap top was shitting itself!!! Noise back.



Aint the amp methinks as the HPA output is fine.



57 folk, tell me its something simple like a cap please.