Do the professional radios have better audio than the Uniden/Whislter scanners? Have used a BC536 and a TRX-2.
If your are talking about a Digital system (P25). Not necessarily, it depends on how the radio's are setup.
I live in a non-simulcast area. The single site I monitor has audio that is borderline impossible to understand. Now and then a voice will come in clear, mostly muddy or screeching. No settings in either radio could much alter it as far as I could tell.
Roughly eight or nine years ago when the first P25 systems went active in my county, I heard some God awful audio from radio's in the field and an occasional dispatch console. Eventually, the various issues (like what you mentioned) were resolved. Today excluding Simulcast issues, the radio traffic I monitor is very clear.
One exception would be Fire Department Respirator Masks. Depending on the make and models of radio's and masks, they can sound very muddy or distorted. The latest generation of properly setup Moto radio's and the latest generation of Respirator Masks have much improved audio, but still not crystal clear in every case.
FYI, I have three digital scanners, PSR-500, Whistler TRX-1 and a Uniden BCD436HP. The best sounding is the nine year old PSR-500. It has the largest speaker, the audio sounds like static free FM analog very natural.
Next best is the TRX-1, but it's small speaker can sound kind of twangy (for lack of a better term). The Uniden 436 has a muddy (overly bassy) sound from it's small speaker. My fix, was to get a really inexpensive set of powered PC speakers ($7 each). They made a significant difference in the audio for both the TRX-1 & BCD436HP.