I migrated to iBroadcast. It's free, and it seems to fit my fairly minimal needs. In particular, it allowed uploading everything I dumped from GPM (~7k tracks

I migrated to iBroadcast. It's free, and it seems to fit my fairly minimal needs. In particular, it allowed uploading everything I dumped from GPM (~7k tracks, apparently), and allows specifying which songs should always be available offline on an Android device. Presumably it has the usual streaming features and online music acquisition features as well, but I don't use any of them. The client has an option that claims to do some normalization that I hoped would prevent large deltas in volume between tracks - in practice this seems worse than what I got from the GPM player. I mostly listen to long heterogenous playlists on shuffle, so this probably wouldn't matter to people who listen to full albums. I believe they have some monetization plan involving allowing higher bitrate playback, but I don't think I can really tell the difference. I did try migrating to Youtube Music first and gave up after one too many annoyances.