Preamp bleeding

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

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

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?

John Atkinson's measurements indicate relatively poor channel separation for the 912, which is suggestive of the possibility that isolation between different inputs may also not be very good.

Yogiboy's suggestion of shorting plugs on unused inputs could conceivably help. Rearranging which inputs are used for which sources could also conceivably help. But I wouldn't be surprised if the only solution is to turn off or mute inputs from sources you are not listening to.

Regards,
-- Al

Jjrenman, yes. example: TT playing through speakers, RTR on and in play mode can hear btw songs.

Is the bleed through coming from other sources that are on but not selected?

You can try using shorting plugs in the unused (if any)inputs!

Sorry, one input to another.

Do you mean left to right channel or from one input to another?

start from swapping tubes.