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Faint hum....

I've been struggling to understand this issue for a while...my integrated amp has 2 RCA inputs, 1 XLR input, and a few digital inputs (Toslink, Coax, etc). When I turn the system on, i'm usually on either RCA1 (CD player) or RCA2 (phono stage connected), there is a low hum in the speakers. If I increase the volume, it gets louder. If I mute the amp, the hum goes away. It's noticeable, but it doesn't bother me when the music plays. What I find it somewhat strange is that it has the same volume if i switch between RCA1 RCA2, and XLR (I have nothing connected to this input!!!). But when I switch from one digital input to another (Coax, Toslink1, Toslink 2), there is no hum. Everything is dead quiet.
So what's going on? Is there anything I can do to eliminate this hum? I tried all sorts of interconnects, speaker cables, the hum remains when I switch from one analog input to another. It might have different intensities, but no cable got rid of it.
iasi
erik_squires
16,009 posts
 
Ground loop on the analog inputs.

Try disconnecting all your analog inputs and add one at a time. See if you can recreate this with either alone, or if it requires both.

Try plugging everything into the same strip, and unplug any coaxial cables involved, such as cable tv/internet if they are one of your inputs.
Post removed 
iasi OP
115 posts
 
i'll try it, thanx. everything is plugged in the same power conditioner, and no cable box or tv in the room.
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