A Cheetah I fly has a couple of these radios. The radios have been to the
factory and supposedly meet specs, and the installation has been checked out
by two different avionics shops with no problems, yet these radios sound
terrible. They garble, distort, flutter, sometimes one or the other can't
be heard, etc. Yet at times they sound just fine.

Is this par for the course with these radios? Or something to do with this
particular installation?

Next year they are getting replaced but until then is there anything I can
do?