Ugh, hit the back button and lost a long ass post. FK. Anyway... I just came across this yesterday. No crashes so far, easy install, noticed improvements right out the gate. Bass more defined for sure, soundstage maybe a tad better, imaging has been locked in so no real change there, overall sound is more defined, smoother, dynamics are improved for sure. Cumulatively it all adds up to an upgrade worth the asking price. I have not tried Jriver and based on user reviews about the experience and no real difference over Kodi or other exclusive mode players I'm not even going to bother. I'm running the trial at the moment and will purchase when the trial is up and I feel that it's stable. First day has been fun I must say. I installed the Intel alternate version, configured with defaults and Kernel streaming, and for one PC. I'm using BubbleUPNP on my phone and HiFiCast on my tablet to see which I prefer. Both seem pretty capable. There's no fancy library functionality like Plex. I'd pay a few bucks more for a dedicated app on Android/IOS/Windows with rich metadata, I find myself reading the artist summaries in Plex and Kodi sometimes and it's a nice feature to have which is missing here in JPlay. So missing in all that is quality album art which Kodi and Plex handle very nicely with Plex beating Kodi hands down. I'm running my library (a copy of a backup of a backup) through MusicBrainz Picard for the hi-rez cover art. Blah blah blah, the sound quality is a solid improvement in my opinion.
I'm using a Lenovo M700 Tiny Desktop with i5 2.3Ghz 4core, 16GB of RAM, 1TB Samsung Evo 860 in the stock floating HDD mount, stock SMPS, and the music is stored on the SSD, plugged into a Panamax M4300-pm on a linear filtered power outlet, via USB to a Topping DX7-Pro DAC connected via Mogami Gold Studio-03 XLR to an Emotiva XPA-2 Gen2 amplifier, Mogami Speaker cable from Tekton (waiting for MOABs to arrive, was told they should be shipping soon) feeding a pair of Magnepan MMG on isolating pucks, and a pair of Polk PSW350 10" subs (so musical when setup right) in stereo on the Topping RCA outputs. Super enjoyable system and so far all upgrades up until this point have made positive noticeable improvements (my wife notices when things have changed for the better or worse and isn't an audiophile per say).
So that's the setup and through it I hear more of the music with JPlay than I have with Kodi, Plex, and AmazonHD. I'd say it adds a bit of finesse to the presentation, allowing you to get some more detail out of the music. To anyone wondering, just grab the trial and see how you like it.
