@analog_man I know this is more than a year old, but maybe you'll see it (or someone else will). I just installed the player code on my core2 device. I grabbed the github version. I have M5Core2 version 0.1.8 installed and initially I had the exact same issues you're describing. The two stations that worked sounded like they were playing at half or quarter speed.
See here for discussion: https://github.com/m5stack/M5Core2/issues/110
The short of it:
replace "M5.begin();" in setup() with "M5.begin(true, true, true, true, kMBusModeOutput, false); ".......
Pretty much perfect playback. I use the following links:
const int stations = 9;// Change Number here if you add feeds!
char * stationList[stations][2] = {
{"Orig. Top 40", "http://ais-edge09-live365-dal02.cdnstream.com/a25710"},
{"Lite Favorites", "http://naxos.cdnstream.com:80/1255_128"},
{"ORF O3", "http://ors-sn02.ors-shoutcast.at/oe3-q2a"},
{"ORF Salzburg", "http://ors-sn07.ors-shoutcast.at/sbg-q2a"},
{"CBC Music #1", "http://26423.live.streamtheworld.com/CBLFM_CBC_SC"},
//{"CBC Music #2", "http://19003.live.streamtheworld.com/CBLFM_CBC_SC"},
//{"CBC Music #3", "http://18063.live.streamtheworld.com/CBLFM_CBC_SC"},
{"WETA Classical #1", "http://17643.live.streamtheworld.com/WETAFM_SC"},
//{"WETA Classical #2", "http://26103.live.streamtheworld.com/WETAFM_SC"},
//{"WETA Classical #3", "http://26153.live.streamtheworld.com/WETAFM_SC"},
//{"Classic FM", "http://media-ice.musicradio.com:80/ClassicFMMP3"},
{"Radio Classique", "http://radioclassique.ice.infomaniak.ch/radioclassique-high.mp3"},
{"Concertgebouw Live", "http://i1.cdn.jetstre.am:8000/sz=RCOLiveWebradio=mp3-192"}
};
I'm right now listening to these and they all work like a charm. Even the 192Kb/s RCO Live (Concertgebouw Live) works. You can check the stream links in VLC to make sure.
Hope this helps.....