All that sais and it is usually referred to as cross talk there may be another potential problem to consider, which is just your phono pre picking up true RFI. I had a friend with that problem and one solution was to use a Faraday cage. I do think it is your tuner. One sure way to be certain is to take the tuner out of your system and hold it in another room entirely. Check to see if you still hear it or not. If you don't go back to the other advice people have provided.
Rogue Audio Cronus Question
I'm just getting used to a new(used) Rogue Cronus (not the Magnum) - and I noticed that if I leave the tuner on (Aux 1) while listening to the turntable (Phono), some faint music from the tuner comes out of ONE of the speakers. It's in phono mode, and obviously I can get rid of the sound by simply turning off the tuner, but why would that happen, and how can I correct? Thanks.