Thanks to you both. Using the RCA input plugs on the back of the transmitter, I've tried all options (CD as the Tape-1 input on the stereo and then Tape-1 out into the transmitter; headphone jack that splits into RCA ends; and speaker terminal connections with RCA ends into the back of the transmitter). I should have mentioned that the bluetooth signal is going to powered speakers with volume control, which is the control I am using to adjust volume. Anyway, there's no difference in audio quality that I can tell, other than I need to keep the stereo volume at a modest level when the headphones or speaker terminals are the source. And also locate the transmitter a foot or two away from the receiver; there is some sort of harshness/feedback otherwise. Given that, the Tape-1 input/output seems to be the "cleanest" signal to use since it's not "processed" through the receiver. And yes, Phil, I can adjust volume separately on two pairs of speakers that way, and that is a scenario that occurs.