Can't believe I've never watched Back to the Future - it's everything I love packed into a movie! Doc really reminds me of Glen George :)
Idea of an Android based music player disgusted me at first, but thinking back, having Syncthing to sync the music would be pretty awesome.
It'd be pretty cool to have a keyboard where controller is a TOMU (BOMU for the wireless version) plugged into a spare usb socket.
Got a Sony NW-ZX507 - using high gain balanced out with CKR100 now. CKR100 sounded brighter than on my phone while still being silk smooth. Before the vocals were on the quieter side, but now everything seems to balance out nicely. My CKR100 is EU's 80 Ohm version, which may be another caveat?
Tried to set up Syncthing for music - actually the primary reason I went with an Android based player - but was disappointed to find out Syncthing doesn't support SD card storage. Setting SD card as internal storage is a workaround, but the Android version on the player is missing the 'format as internal' option. Bummer :(
I was able to disable most of the google stuff though, which is a neat. F-Droid works nicely, and grabbing apk from non-Google app stores/sites is pretty straight forward. Although somehow system search relied on google service - hmm, makes you think, right?
Battery life is not stellar - but something I can get used to - I got to 50% after 8-10 hrs of listening to a mix of flac/hires flac/aac. I mean - back in the day we didn't have to charge our phones for weeks, but look at us now. It does finish charging within 2 hrs or so with a fast charger which is nice.