Loud hum in one channel

The hum switches when I swap interconnects from the table to the preamp, and the noise only happens when I am using the preamp setting for the turntable; in other words, it does not happen with the CD players. BTW, the noise is present even when the TT is off, and with JUST the ground wire attached and not the interconnects; is that weird???

Puerto, yes the hum is present when the preamp is set to TT but not on CD or AUX. I will disconnect the ground wire as soon as I get home and report back. Thanks for your help!

Here's a follow-up: Disconnected TT and ground wire, and noise like jet engines coming out of both speakers, more so on the left, but only on the TT setting, not the CD. Re-connected the Empire, and very noisy on the left channel, not so much on the right. Finally, I connected my Funk TT and also noisy, although nowhere as much as the Empire, and more so on the left. When I connected the Funk TT to the CD interconnects, I get no noise.
The phono amp in the pre-amp was installed when I bought the Prima Luna pre-amp. Is this the culprit?

Thanks, guys. You know, I was never enamored with that phono preamp that was installed, and I wonder why it took the Empire TT to bring out all the bad in it, when the Funk was playing not too badly. At any rate, I will shop for an external phono pre-amp and try it that way. I hope that is all there is to it.