Catch22 wrote:

Just another possible consideration. Hums are often grounding issues, but don't discount the tube creating the problem. It could be a simple reseating of the tube in its socket or replacing it. 12AX7 tubes are prone to being noisey to begin with and I would think it would be particularly problematic in a phono stage. I had to replace one just a couple of weeks ago that had become microphonic and was humming its own tune.

Touch the tube with your finger when you notice the hum and see if it changes pitch.

Actually it does when I touch the tube! It functions on what feels like a much lower wave.

commsysman wrote:

The fact that it changes when the signal changes indicates to me that the problem is in the circuits of the phono preamp. I don't think anything else could do that.

It sounds as if the phono preamp circuit has some sort of internal grounding problem. There could be a loose connection or cold solder joint in the wiring.

I would open up the preamp and look for any loose mounting or grounding nuts or screws.

I would also make sure there is a ground wire from your amplifier chassis to the phono preamp and turntable grounding point. They should all be tied together to a good ground. Since your wiring may not include a good ground, it would be good to get a grounding clamp and clamp it to a metal water pipe and run a wire from it to your amplifier chassis.

I cracked it open and things look ok: http://imgur.com/n8Nm6Es But I will look into figuring out a way to ground it to a metal water pipe since one is in another part of my apartment. Also, currently there's no amplifier in the set up since I only use the Bellari as a headphone amp.

Catch22 wrote:

Sometimes just reseating a tube cleans the connections well enough to get rid of a hum, but it's always a good idea to have a few (hundreds in my case) spares. lol

Thanks! I tried reseating it and putting in the stock tube (Ruby 12AX7AC5 HG) it came with. Both displayed some hum, albeit a little differently. Is it just bad luck or do you think something's wrong inside the preamp?

Also the hum disappears when I unplug the RCA inputs in the preamp.

I just fiddled around with the headphone jack and noticed if I rotate the 1/4 to 3.5mm adapter to a certain position the hum stops. However, when it does stop the music sounds like it's playing in a tin can.