New answer to this question. Any station that does not encode with this PPM crap is the best sounding station. This PPM has ruined every station I have heard. Even awesome sounding cox radio stations sound like garbage. so thanks for ruining radio PPM...... And somehow, talk makes it that much worse... I guess music is doable but listen to talk programming and you will long for the pre ppm days. at least I do......
The PPM does not degrade the audio.
What can degrade audio is the use of third party processing to try to enhance the audibility of frequencies that then allow the PPM encoder to activate. Overly adjusted, that causes unnatural enhancements to audio that make the sound potentially dreadful.
And, in PPM markets, with perhaps one exception of a significant non-commercial contemporary Christian station in Orlando, every station other than a few peripheral AM stations, is encoded.
Outside the 48 PPM markets, stations don't encode and don't do the encoding enhancement.