A few weeks ago, I found this neat little switcher from Realistic for 7$, the Realistic Tape Control Center. I can now hook-up 3 tape decks; listen, record from one or all three or just from the source. I have put my tube Yaqin 6J1 tube buffer in the loop. If I select tape from my Yamaha controller, I can pass the signal through the tape control center and get amplification through the buffer. Neat. The control center works very well, no perceivable loss of signal or interference, and now, I am not getting "hum" from the buffer.
Realistic Tape Control Center
Yaqin Tape Buffer with 6J1 tubes and 2 Lepai 2020+
mounted vertically by me...
I can now control 3 tape decks with 1 input to the Yamaha controller.