Mike, Bill is probably right,
Check and adjust your BFO first. That is
almost always the reason for poor voice quality,
especially since others are using the more or
less the same setup and not reporting problems.
You will have to reload the software (maybe several times)
adjusting the BFO frequency until it sounds right. First,
use a frequency counter to find out what the present BFO
is. Record it so you can always reset it if the problem
turns out to be something different. Then find out what the
software says is your BFO and adjust it up or down by
500 Hz or so. Check the results and go from there...
It is relatively easy with a VFO, but using software makes
the job somewhat harder.