Acceptable speaker hum from integrated or sign of impending failure?


I have two integrated amps that are now about a decade old and one produces a slight 60 Hz hum that is audible < 6 inches from speakers when power is on and no inputs are connected- the other is dead silent. The hum doesn't increase in volume as the knob is turned and is constant. I've moved the "hummer" to different circuits and no matter where it is plugged in or what is plugged into the inputs or outputs the hum is audible. Also tried swapping the three prong cords between the amps and this has no effect. Only had it a week or so and am not sure whether the hum is new or was unnoticed previously. Is this an acceptable shortcoming? My main concern is whether the power supply or any internals may be going bad and causing the hum.  Any thoughts greatly appreciated!
joincoolkidclub
my guess is that if it's audible within the chassis that it's more likely a problem with the internals of the unit itself (loose transformer, failing power supply, caps, etc.) than with the  ground or power, but it could be a number of things. i certainly don't see any harm in tightening the torroidal transformer before moving onto other causes. be careful
Unacceptable to me.   I can put my ear to my speaker with volume up and no hum at all.  Send it back to the manufacturer
@loomisjohnson Sorry, meant to say that the hum is not coming from the chassis, but the speakers only. Will leave unplugged and see about taking apart tomorrow.

@stringreen Unfortunately I am not the original owner and can't imagine that the unit is covered under warranty. Having the hardest time getting in touch with Simaudio anyway...
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