I just received my R4 and did some tests with the 'Device Info HW' app listed in a post above. I played an album through HiBy Music, with no PEQ, MSEB, or Plugin active. I then did the same thing with a system-wide PEQ filter (low-shelf), MSEB active (overall temp. slightly darker), and DRX10K plugin active. I ran the test with my Sundara (4.4mm balanced) and Moondrop Para (3.5mm SE). I choose Para because of its low impedance.
Here are the 'quiet-therm-adc' plots:
So, everything appears normal, my R4 does heat up, but slowly... I stopped the tests at 25mn, but I assume the temperature would stabilize around 42-43 degC.
Temperatures and rates are a little higher with the balanced output (as expected) but nothing to worry about.
My music library (~13k tracks) is stored in a OneDrive account. I used OneSync to mirror it through WiFi. With the "parallel download" setting enabled, it did crash the R4 several times... Severely enough to require a hard reboot in some cases!
Wondering what happened, I did another test with OneSync running in the background...
The orange curve below represents the R4 playing the same album through HiBy Music and Moondrop Para (3.5mm SE), no PEQ, MSEB or Plugin enabled, same volume. So, the most favorable case... but with OneSync running in the background (sync'ing tracks).
Note the different Y-scale:
The difference of behavior is quite staggering. It's obviously not enough data to draw a definitive conclusion, but I wonder whether
thermals are going to be the R4 limitation: perfect to play music, even with a bunch of DSP effects active... but don't try to run CPU/GPU-intensive apps !!!
My M300 only shows 'xo-therm-adc'. On the R4, 'xo-therm-adc' seems to parallel 'quiet-therm-adc'. Noticeably, my M300 'xo-therm-adc' stays in the 29-30 degC and does not appears to change much. After all, there may be a reason why the R4 is an "audiophile" oriented DAP (to play music...), whereas the M300 is a "lifestyle" oriented DAP (to play music and do other things).