Please only post once per issue. It's confusing for those trying to answer you.
Sorry about that -- thought I may have posted it in the wrong forum. Thanks for deleting the duplicate post.
1) How loud is this hum, compared to the music being played?
It's much lower than the music and barely audible while the music is playing.
2) Does the hum go away when you touch the tonearm?
3) Is the hum audible when the turntable motor is off?
4) Did you previously use the Eros with another turntable?
Yes, I previously had a Gemini TT-01 hooked up and there was no problem. This turntable had a connection for the ground post, though, which is why I suspect it's something dealing with this.
5) Have you used this turntable with another preamp?
No. Good call -- I'll try that now. <couple minutes later> Ok, tried it with some pre-amp I got at Guitar Center a while ago (WOW! What a difference in sound! This is the first time doing an A/B comparison!). There's some ground noise in there too but it wasn't as loud. I'm guessing that this rules out the unused Eros ground post as the culprit then?
6) What are the components of your system?
Orbit -> Eros -> Sony CMT-NEZ3 (don't judge! I have a Stereomour II kit en route!) -> Klipsch RP-160M speakers