Just a quick post: Last night I dug out my X5III which I hadn't touched for at least a year--1.2.5 vanilla FW--as I was curious as to how it would play with my Custom Cans Grill modded Edition XS.
I had to recharge it from zero which was faster than I thought using the dual voltage charger from a Samsung smartphone, plus had to swap in an alternate USB Micro-B cable as the FiiO didn't like the first one.
Once it warmed up and I had rebooted it 3 or 4 times, the Tidal version 2.31.0.1010.16 Android app (Sep 2020) still worked smoothly enough, although stuck at the High Quality (16/44.1) for all songs (which is fine).
Anyway, once it had the cobwebs out I was very pleasantly surprised at the really good sound quality and synergy it had with the EDXS using the 2.5mm jack with "turbo" selected in audio output. I mean it actually really got my attention on a couple of songs, just nice full bass and soundstage and great clarity. I guess those dual AKM 4490EX are still no slouch. Of course the unit is beset by a really slow processor and can be very frustrating, but like in the past, if I give it a few reboots and let it get settled, be patient, don't throw more than one task at it at one time, it can still be a satisfying musical experience!
Oh, and battery still solid for a unit bought at the end of 2017.
EDIT 4 FEB: Battery is draining faster than I initially thought but I can still get maybe 2-3 hours out of it from full charge. Not surprising and still pretty good for a mostly dormant DAP since 2021.
Edit 4 FEB: FYI, in my vanilla FW version, the the latest version of UAPP is essentially unusable. I had a previous version on there which was also basically the same but thought I would try and see what the new regime (Hi-Res FLAC) would be like. I did get a 24/96 song to finally play but it took so long to get there that it wasn't worth it. The modern UAPP is Just too demanding for the X5III (not sure how the Custom Kernel handles it) although there might be a long ago version that's usable similar to the my 2020 Tidal version that works OK, but is somewhat slow to get going. Kind of surprised that even with Android 5.1 UAPP is still supporting it.