This is a review and detailed measurement of the Android basaed HiBy R6 Pro Portable Digital Audio Player (DAP). It was kindly loaned to me from an overseas member. The R6 Pro costs US $549 from Hiby's own store.Any resemblance to a modern mobile phone ends with the Android OS. The R6 Pro is very heavy, thick and chunky compared to any mobile phone:One advantage over any mobile phone is hard switches for standard transport control (play, pause, etc.). Another advantage is ability to act like a DAC over its USB-C port and a Coax digital input.Personally I think Android brings way too much software for just a music player. Changing the language from Chinese to English for example required digging deep in settings to do (thanks to members who helped me do this).While I did not play with the unit much, the touchscreen was quite responsive. The display looks dull but this could be due to settings for it.For my testing, I connected a USB-C cable to the R6, selected the option to act like a DAC somewhere in the menus. The unit was detected nicely as a DAC by Windows 10, allowing me to run the full suite of tests I run on DAC+headphone products.DAC Audio MeasurementsAs usual, we start with our dashboard. Here is the output at full volume:We see a spray of harmonic distortion reducing performance. Thinking this may go away at lower levels, I reduced the volume to 2.0 volts which desktop DACs typically produce but that did not help:Overall ranking is not good as a result:We can see why distortion did not improve at lower level we sweep that while measuring intermodulation distortion:We see that distortion takes over noise at -25 dB and stays there. Very disappointing.Speaking of noise, that performance is good:Frequency response is flat enough:Jitter test shows some bad bits here and there but overall, not an issue:The real head-scratcher was linearity:As you see, it has a mind of its own, resulting in 1 dB error. Due to its time-dependent variability I could not replicate it in static measurements to see what is going on.32-tone test resembling music shows a mess of intermodulation products, increasing with frequency:So in some sense the dashboard is doing the R6 Pro a favor by using a low, 1 kHz tone. Then again our threshold of hearing increases in higher frequencies so the distortions tend to be less audible there. Yeh, I am trying hard to put a positive spin on this.Let's see how much power we get with 300 ohm load:That is disappointing. What is all that weight going to if it is not a beefy power source and plenty of room for a powerful, higher voltage headphone amplifier?Since the DAC portion is used in these tests, it serves to raise distortion just the same, making for a sour soup.Here is what we get at the other extreme with 33 ohm load:As with 300 ohm load, distortion starts to increase at such a low power level (again due to the DAC failing). Here, we get hard clipping due to running out of current at 190 milliwatts.To test the effectiveness of 4.4mm "balanced" headphone output, here is the performance using that, versus 3.5mm jack:So we get about three times more power which should come in handy with low impedance headphones.Output impedance was comfortably low:I started with my Drop Ether CX 25 ohm headphones powered by the 4.4mm balanced output. Performance here was good although I could get the output to distorted if I went above normally comfortable power levels.I continued with my Sennheiser HD-650 using the 3.5 mm jack. Here, I was pleasantly surprised that there was decent amount of power available without much hint of distortion. Balanced output would have provided some headroom (I did not test this).So overall, the subjective performance is better than objective data, likely due to ability to provide more instantaneous power than continuous.The objective performance of HiBy R6 Pro is low with strange anomalies in linearity test. Nothing stands out as exceptional which is disappointing given the fact that one invests in these devices to get much more performance than a mobile phone. My recommendation is to get a LG phone and use it as a dedicated player. It will be much lighter, come with better software support for the OS (as far as security fixes and such). But I understand people valuing the hard buttons and such on R6 Pro.--------As always, questions, comments, corrections, etc. are welcome.Have to run out and fix our greenhouse which has become a crooked mess due to winds working on its flimsy build. Being very big, I had to hire help to clean it up and help with the reconstruction. The bill will come later today so I appreciate any monetary help so I don't feel poor after that. Pleaseusing : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/