System Hum Question

However, when I disconnect the inputs from the preamplifier (and leave the other end connected to the amplifier), the noise in my speakers gets louder. Why is this?

No doubt.... Don't do that. Having the ICs connected to the amp but not connected to any thing on the other end works like an antenna and will introduce large amounts of RFI and EMI to the input stages of the amp.

Not good on the speakers either.

Hi Bongeiste,

I just had this problem. One of your source devices (CD player, turntable, or tuner) has a 60 cycle hum on its audio outputs. Disconnect one source component at a time until the hum disappears. Then take the source component in for repair.

It's been a few days, so I'd like to partially close the loop on this issue. A few days ago, there was no hum when I turned my system on. This isn't unusual as the hum comes and goes with no discernible pattern. I also installed beefier interconnects between my amplifier and preamplifier. To address an issue raised in an earlier reply, I only have my computer hooked up to my system. I don't have any other components right now. The computer is attached via TOSLink to my preamp. One night when my system was humming, I shut my computer down and unplugged it from the wall. The humming persisted, so I surmised my computer was likely not the cause of the hum issue I was experiencing. I haven't heard anything about TOSLink being a source of hum either, so I ruled that out as a likely cause.

Fast forward to today. I'm on Day 4 with no hum. The absence of hum may simply be due to a neighbor who went on vacation or my issue may truly be solved. I won't know until more time has passed.

Thank all of you who replied. I'll certainly keep your replies in mind should the hum reassert itself.

Do you have florescent lights in your home? If so make sure they're not on. There are several things that can be on that will cause hums through the electrical network.
Good luck.