Maybe all this is a sound card problem.
I stream a few feeds and couldn't understand once why a certain feed was coming out my speakers when I'd selected a different feed. I checked cables, scanner frequency selections (all the obvious stuff I thought), and finally realized one of the sound card settings were off.
I don't feed directly to Dave, so not sure exactly how you guys stream your various feeds, but I'm sure there are multiple audio cards involved for those feeding more than one set of frequencies. I'd be double checking all those computer settings at both ends. Dave's and the ones near YYZ.
Just a thought.