Preamp bleeding

What Al said. It is not uncommon to get some bleed through from other sources into the selected source.

Is there a reason you need to be playing the RTR at the same time you are listening to the TT through the speakers?

Jjrenman, no reason at all except to see if it happens. Only does it with the RTR playing.

Contact the distributor/manufacturer. Could be a sign of further trouble to come.