Speakers Connected to PC are Humming

[Guest]

Yes, I know it's an oldie but goodie.

Speaker/Headphone outputs (both front and back) on PC connected to AVR or Amp produces discernible hum through the speakers. Cable is 3,5mm to RCA.
All devices are on the same power circuit and I have thrown a ground loop isolator in there for good measure.
Little AC powered computer speakers don't have this problem.
PC also has HDMI output which is fine.

Any words of wisdom?

 

[anbello262]

Is the sound persistent, or does it only sound under some kind of trigger? For example, I've seen cases when the noise would only appear when the mouse was moved, or when the monitor image was changing.
So, do you hear it all the time, or when you do something?

 

[Guest]

Is the sound persistent, or does it only sound under some kind of trigger? For example, I've seen cases when the noise would only appear when the mouse was moved, or when the monitor image was changing.
So, do you hear it all the time, or when you do something?

It is a constant hum, whether or not I am playing any audio.

Edit :

I have just now used a 3.5mm to RCA adapator and run a well-shielded component video cable (2 out of the 3) and speakers connected to the old amp are now hissing, not humming, but the speakers connected to the AVR are good as gold. Problem solved - just need to check up on the amp.

 

[anbello262]

Ok, great it has been solved. Good luck!