The channel workaround did not work for me either. What did work for me was lowering my audio quality in my Realtek HD Audio Manager. I had mine set on max but I lowered it to 24bit 44100hz which fixed it. Other levels worked also.
I noticed as well that the sound echo definitely started happening after I lowered the volumes in game so I could hear my friend on axon as we were playing together.
I'm only posting this to give the people something else to try if the volume 100% trick did not work. Hope this helps someone.
