This is a review and detailed measurements of a bare board LG G5 Hi-Fi Plus DAC and headphone amplifier. As the name indicates, it is an accessory piece for the LG phones to increase performance. However, it seems that it is available as bare board which is sold in Asia for as little as US $20. A member kindly purchased one of these and sent it to me.The version I have came in a clear case which is much needed given the delicate nature of the two board solution:The included case does not do a good job of containing the USB-C connector which moves with ease as the cable moves (not good).I was unhappy with the cut-out for the headphone jack as it did not allow me to use many of my cables. It requires a skinny headphone plug which fortunately is the case with many modern headphones.Typical of these devices, there is sensing of the headphone jack to both enable the device to function and also set the output voltage. You have to have something plugged into it or it won't be recognized by the host device.I was very pleased to see a ASIO driver for Windows including one of the nicest looking control panel. Alas, no matter what I did, I could not get the control panel to recognize the Hi-Fi plus. Windows would recognize it as an audio/video device but oddly, not show it as a list of selectable audio devices. This put me out of business as far as fully testing the device using my Audio Precision analyzer which expects a working Windows audio device.So for my testing I resorted to Neutron audio player on Android. The app nicely recognized the device and was able to support even 24-bit playback.In even light use, I noticed the plastic case starting to warm. Together with this, the output dropped progressively. The best I got initially was 1 volt which is less than what others have gotten (1.9 volts). But that was temporary as the device proceeded to drop to 0.9 volts. Later in testing with low load of 33 ohm, the output dropped much more to just 0.3 volts. Whether that is due to high output impedance or protection circuit, I don't know. I understand some versions of this board come with a metal case. I highly suggest that option over this plastic one.I played my 24-bit, 44.1 kHz Sine Wave tone from my Android phone through Neutron app and got this:This was with no load on the device (as I typically do for DAC testing). If Channel 2 was as good as Channel 1 at 109 dB SINAD, that would be exceptional. Alas, it is not so I averaged the two and got 106 dB:The LG G7 I tested got a SIAND of 105 dB so this is not much improvement over that. Of course if you use this dongle with other phones like my Samsung S8+ used in this testing (SINAD 89 dB), you get quite a boost in distortion and noise.Next I ran my jitter test:Wow, this is very clean! It shows how little some companies put in design when they get super noisy spectrum. Most dongles don't do this well.Lastly, I ran an old test with -90 dB sine wave to see if the device can resolve such a small signal correctly:The sine wave is nicely resolved with just a bit of noise which is normal.Stuck with low output level, I started my headphone testing with my closed back and sensitive AKG K92. I was forced to listen at or near max volume but what was there was quite pleasant. I did get some clicks on one of my music files but not sure if this is a player issue or not. On other files, the results were fine.I next tested the unit with KZ ATE Copper Driver IEMs. I was surprised that levels were quite low. No doubt the low impedance had forced the unit to cut down even more in power. So again I had to listen at or near max level. Doing so on well recorded material sounded quite nice.We couldn't run our full suite of tests on the LG G5 Hi-Fi Plus but what did run, showed excellence in design. We have a low noise, and low distortion dongle here.I am not a fan of what I received in the form of this clear plastic packaging. The metal ones may be better. And if you can get the unit to output higher levels, then you could be set with a very high performance dongle. As it is however, it is too much hassle for me to recommend it.-----------As always, questions, comments, recommendations, etc. are welcome.Get this: one of the panthers is begging me for plastic surgery. I can't tell you what organ he wants enhanced but I let you guess. Putting aside that I can't even find a plastic surgeon for panthers let alone one that performs such operation, lots of cost will be involved in it for sure. So pleasegenerously using the links below. Help him get his self-esteem back! https://www.patreon.com/audiosciencereview ), or https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).