> Off topic, but I've noticed in the gym, sometimes the music playing from the instructor's iPhone through one of those cheap Ion Block Rocker bluetooth speaker

> Off topic, but I've noticed in the gym, sometimes the music playing from the instructor's iPhone through one of those cheap Ion Block Rocker bluetooth speakers (big boxy one, looks like a guitar amp) has very very noticeable pitch sag in various parts of various songs. Many Bluetooth speakers are not loseless. Cheaper ones are likely going to support MP3 and that's it (or even worse, just the minimum required SBC). Pandora is already compressed, if your instructor doesn't know to flip the "HQ sound" toggle (which is turned off by default on Mobile, even with a paid subscription!), then 128kbit MP3 recompressed to MP3 yet again, is going to sound pretty atrocious. Not sure if one of the other codecs used for A2DP can cause pitch changes though.