This is a review and detailed measurement of the ifi nano iDSD Black edition portable DAC and headphone amplifier. I purchases this a few months ago from Amazon for USD $199 including shipping.A lot of desktop and portable audio products I review are utilitarian and don't evoke much emotion. But there are some exception and the ifi nano iDSD BL is one of them. It is pretty cute!The volume control feels nice. The metal enclosure also feels quite stout.Included in the unit is their IEMatch resistor divider to lower noise and increase volume control range in case you need it. See my review of that functionality here: https://www.audiosciencereview.com/...asurements-of-ifi-ear-buddy-and-iematch.4707/ The only input is USB. For good or bad, this is the funky iFi male USB connector which necessitates using their cable to connect to your computer. They say this makes it more convenient to hook up portable devices to it. For my use, I don't like the very stiff USB cable. It easily tugs at the unit and is short to boot. It is also blue as you see in the above picture instead of black that I would expect. So you may want to get an aftermarket cable.For output, in addition to the two headphone outs, there is also line out which I appreciated for my measurement purposes.Speaking of measurements, this review would have come sooner had I not experienced some serious issues at first. First problem was getting the unit to be recognized by Windows. The green light would blink and Windows would not show it as a device. Installing ifi drivers did nothing to remedy this. On a hunch, I connected it to my USB 3 ports and that resolved this problem and I could talk to it using both ifi and native windows drivers.But then the performance was awful. There was a lot of harmonic distortion with performance easily 20 dB lower than advertised (and totally non-competitive). Fortunately I remembered that many portable devices demonstrate a lot of distortions if their batteries are fully drained. Since this unit had been sitting in its box for months, I figured that may be the problem. So I turned it off and let it charge for a few minutes and the problem vanished.The two issues were related since getting it to run initially required more current than my standard USB 2 port on my desktop machine can provide.Anyway, with everything sorted out, I was ready to make my measurements. Let's see how she did.As usual, we start with our dashboard view using the line output to determine the DAC subsystem's performance:Output is a healthy 2.1 volts which is nice (2 volts nominal is what we like to see).Advertised THD+N is 0.004% which we are beating at 0.002%. So that is good. Alas, that kind of distortion is nothing to write home about as we see in this graph of SINAD (signal above power of noise and distortion):For comparison and in the same class of product, I am showing the Topping NX4 DSD which betters it by some 11 dB!The performance though is similar to that of ifi Nano iONE . So seems like the same subsystem is used in both.Likewise dynamic range falls in the same class of "OK" but not fantastic:Rating here is 109 dB so we are not quite there but there can be differences in measurement bandwidth.Jitter and noise measurement is good:We see some tiny spikes but they are below -130 dB so no worries at all.Let's now measure the headphone output at 300 ohm:Power is decent but as I show again, the Topping NX4 DSD has more. Same competitive picture remains at 33 ohm:Output impedance is very low and good at 1.0 ohm:So it should be able to drive just about any headphone without audibly changing its frequency response.Finally let's look at channel imbalance (blue) versus volume control position:While spec compliant, there is a lot of deviation at levels go down.I started my listening tests with my Sennheiser HD-650 headphones. The sound was quite nice although I had to turn up the volume to 3:00 o'clock from a max of 5:00 o'clock.Performance with my Hifiman HE-400i was not as good depending on what I played. Bass is anemic here requiring more power than the nano iDSD BL can produce at times.Overall, there was enough power here to get loud but not impactful. Personal preference and headphone type will determine if you get the same experience as me or better/worse.I was very inclined to like the ifi nano iDSD BL from its good looks and fond memories of testing its larger and excellent brother, ifi iDSD Black which I reviewed recently. Alas, downsizing the unit has hurt performance with power levels are a bit too low for my taste. The chunky size of the unit also limits its usage some in portable applications (I can't see anyone rubber banding this to their phone).My recommendation in this class would be the aforementioned Topping NX4 DSD . It has more power, slimmer case, better measurements and costs less ($160 vs $199).Mind you, the ifi nano iDSD is not "broken" in anyway. It just sets lower targets and meets them. So if you want a product from a western company with better direct support, it would be a good option. Just make sure your appetite for power is not as much or more than mine.As always, questions, comments, corrections, etc. are welcome.-----If you like this review,using Patreon ( https://www.patreon.com/audiosciencereview ), or upgrading your membership here though Paypal ( https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).