This is a review and detailed measurements of the xDuoo Link USB-C smartphone headphone adapter (DAC & Amplifier). It was kindly sent to me by a member. The Link costs US $48 on Amazon including free shipping so it is on the premium side of these devices.One look at the Link though and you are convinced you are getting your money's worth:Even the orange packaging it comes in is beautifully designed. There are a set of volume and play/skip buttons on the other side which likewise have excellent feel and usability. All in all, I was most impressed with the xDuoo externally.For my testing, I used my Windows Desktop machine's USB-C port direct into Link. xDuoo does not provide an adapter for typical USB-C port on computers so make sure you pick one up if by odd chance you want to use it on the computer.As usual, we start with our dashboard view of feeding a pure, digital 1 kHz tone and see what all comes out of the unit (with no load):Well, I am quickly disappointed with 1 volt output. This is typical of many of these dongles and immediately tells me it won't have much power to drive high impedance headphones (300 ohm and higher). Power = Voltage * Voltage/Resistance. So if you don't have a lot of voltage, you don't have a lot of power either.Measured distortion is higher than specified which is another disappointment. While there are a lot of dongles in this territory, when you pay a premium, you expect lower noise and distortion. Here is where the Link ranks among all DACs:Jitter and noise is typical of these products:Intermodulation noise is good though:All of the above are with essentially no load on the unit, tested as a DAC. Let's put 300 ohms on it to simulate a high impedance headphone and see what we get:That's not good. We have similar power to Apple dongle which retails for just $9.The situation gets much worse with low 33 ohm impedance load:There is a design problem where distortion shoots way up before it runs out of current and severely clips again. Using the first burst of distortion, power is negligible at just 1.8 milliwatt. You get that much probably from your phone alone. Allowing for much more distortion, we get to the advertised 32 milliwatt spec.Output impedance is very low and hence excellent:Performance with my Sennheiser HD-650 was OK. There was not a lot of bass impact and levels were just adequate. Switching to much lower impedance hifiman HE400i produced a bit more volume but I could sense distortion during music passages with bass.They say don't judge a book by its cover. That is so true here. What looks remarkably nice and usable, lacks the guts to provide real performance. The mechanical designer deserves an A+ for the way the xDuoo Link looks and operates. The electronics designer though has failed us. Given how much larger this device is than a typical dongle, there is no excuse for providing so little output power.Sadly I cannot recommend xDuoo Link.------------As always, questions, comments, recommendations, etc. are welcome.As you see and I reported a few days ago, the "I don't know" panther suffered a major injury and lost one of its arms. Now the rest of the panthers are worried about the dangers of working for me and are demanding body doubles for risky shoots! I am thinking of buying some plastic panthers but that means spending boat load of money. So please help me byusing