I think I might be experiencing a similar issue. When using either Google Play Music or the built-in Samsung music app and playing back mp3s that I personally encoded, I hear all kinds of strange artifacts (clicks, pops, other strange high-pitched noises). These artifacts occur at the same point in the songs and seem to occur for every song I listen to.
I also tried using Shuttle+ for playback and experienced the same problem. However, when playing back FLAC files or AAC files I don't get any artifacts or other distortion. Also, when playing the MP3s through Poweramp I don't experience any artifacts at all. So for whatever reason, when I play my MP3s using the Samsung Music app, Google Play Music or Shuttle+ I get artifacts. They play back on Poweramp with no artifacts. FLAC and AAC doesn't seem to do it no matter what player I use.
I went so far as to copy the MP3s from the Note to my girlfriend's iPhone and play them. No artifacts. Also played them back on my computer with no trouble. I even re-ripped the CD and re-encoded the MP3s and still had problems on the Note.
I'm at a complete loss here. If there was a hardware defect of some sort I would think I'd hear artifacts on all formats and for all playback apps. But I only have issues with a specific file format on certain players. This really bites, because I don't want to re-encode 10,000+ songs.
Has anyone else experienced anything quite like this? I've had the Note for less than a week and really like it otherwise, but this whole MP3 thing is a major deal breaker for me.