I’m using an RME BabyFace.
As Fredo said it’s an inherent problem with phone lines, by definition they loop back because they are a 2-wire circuit (both send and receive on the SAME wires) not a 4-wire circuit.
There are vastly different qualities of phone hybrids, we deal with them all the time. The passive units are terrible. The JK analog units are mediocre at best. We’ve had the best results with the Telos units and the Telex TIF units. They are both rentable.
I’m using a Gentner SPH-3A. I don’t see how quality of hybrid has anything to do with this.
Seems like I need to play the track from another computer. It would be nice if I could do it all from one computer though.