Tbh for the past 6 months I've been fiddling around with tons of different music players. Xenoamp, poweramp, Google play music, clean music player and none of them is perfect. Poweramp is paid and overloaded + not that good on battery, xenoamp is horrible with battery and cpu usage + it's ui is a nightmare, clean music player is crippled horribly and Google play music is terrible with local files. I got a xposed module to make it better but it took ages to play if I quickly skipped like 30 tracks in a row. Ultimately I went back to my own player and god it's good. It changes songs almost instantly. It actually goes to another file as represented by the ui. Gpm does this smooth ui transition to next track that is completely irrelevant to the file played. I genuinely think this is the best music player available for android at this time.
I don't want to make ANY promises, but I am thinking about getting back to its development. Currently I'll be busy with school and my kernel development for Z1 so it won't be anytime soon, but I think I might actually get back to it. Previous track on shuffle is not going back, but playing current track from start. I think I might try again to fix that, but again, it's just me thinking about it. I'm not saying that it will be done tomorrow or in a month. I might never do this. The last time I tried to figure it out it didn't go too well, but I really think it's worth a try.