Reel-to-Reel tape deck audio problem

[user181]

I'm not sure if I correctly understand everything. Are you saying that you're trying to connect a reel-to-reel tape recorder AND a cassette deck? If so, you'd need an amp/receiver with two separate tape loops. I looked at the manual for your Pioneer, and it only has one from what I can tell.

If you want to use both the R-R and cassette with that receiver, you'll either have to resort to cable-swapping when you want to use one or the other, or find an external switch box for multiple tape loops.