Rogue Audio Cronus Question

The first thing that I would do is double-check your cable routing. Make sure that the tuner interconnects are well away from the phono interconnects. Phono gets the largest boost in signal strength in a system so any stray noise will get boosted along with it. It's also especially important to keep phono interconnects away from power cables for the same reason.

My Tivoli 2 radio does this. Never knew it was a cross talk circuit thingie, but that makes sense.

As others have said it's called crosstalk and the phono input is most susceptible because of it's high gain (relative to the other inputs which are line-level).

Use short, shielded phono interconnects and route them away from other cables. And just turn OFF your tuner when not in use, no big deal.

My Cronus Magnum used to bleed thru to the speakers ever so slightly when using the headphone section. It was enough my trying-to-sleep wife would complain.

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.