I think you are already on to it. There should be no problem using the record output jacks from your Yamaha to listen to radio.
Just to be on the safe side begin with your new preamps volume all the way off and bring it up slowly. Probably not necessary but provides a margin of safety for your test.
Just to be on the safe side begin with your new preamps volume all the way off and bring it up slowly. Probably not necessary but provides a margin of safety for your test.