I am loving my R5II. I am not an audio reviewer so take this with a grain of salt. I sold my M3X to go for the R5II and am not regretting that decision at all. The only thing I miss is the slightly smaller size of the M3X. DAPs are about portability for me and I just don't like huge clunkers. I have previously owned Fiio M9, Fiio M11 Pro, Shanling M2X, Shanling M3X, Hiby R2, Hiby R3 Pro Saber, Hiby R5 Saber, Hidizs AP60, Hidizs AP80 Pro & AP80 Pro-X, Sony NW-A55. No complaints at all about the sound. Drives my HD650 beautifully (Class A mode, 4.4mm out). I am using it mostly with Moondrop Kato, Hidizs MS2, Thieaudio Legacy 3, HD650, HD599, HD569, and MSR7b. I am not overly picky about sound, but this DAP sounds as good or better (in some cases MUCH better) than any DAP I have owned. It is every bit as satisfying as the desktop units I have owned or currently own (Loxjie D30, Topping EX5, iFi NEO iDSD, iFi Zen DAC, Khadas Tone2 Pro, and a few others). It is definitely detailed/clinical as opposed to warm/smooth, but that's my preference. Makes it a perfect match for the HD650 (IMO). The Class A mode makes an audible improvement to my ears. I won't use it all the time though because it annihilates battery life. Side note - Does anyone know if it is bad for the device to use it while charging? I feel like I had a Shanling DAP that stated in the manual to not use while charging? Been wondering about this. Also I wish there was a plastic case. I'm not big on leather cases for my DAPs. Although the included leather case is not too bad. I'm sure someone will make a plastic case eventually. In any case, may be my favorite DAP yet, and I plan on holding onto this one for a while. . .
The UI can be a bit slow at times but that hasn't been a real problem for me. Using Neutron, UAPP, Poweramp, Tidal, & Nugs. Also tried it out as USB DAC from my computer via JRiver. No issues and sounded just as good as using it purely as a DAP. When I first turned it on, I had the issue which I believe some others mentioned above, where songs would randomly skip (2-3 seconds of silence and then resume). This was highly frustrating and made me nervous about potentially having to return it, but after a simple restart I have not have that problem again. Also, I greatly appreciate the inclusion of the 2.5mm port. I have many 2.5mm cables that I use with my AP80 Pro-X among other things and it's nice to be able to switch to the R5II without having to change the cable. Although I'm also really enjoying all the modular IEM cables coming out lately by Tripowin, Kinera, etc. Overall very pleased with this DAP. Attached are some pics.