hello,
I know that i can't answer your question, if some time BreakawayOne will have phase calibration, but your problem you have it looks like from your transmitter site. Even your audio cable from your soundcard to the transmitter. BUT of corse if your soundcard is a good one. Hope this info help you.
This photo provide my setup with a good soundcard (marian trace8 ) with 30m! cable (RG223 broadcast cable) from the soudcard to the transmitter.
Best.