This and That:
Nicely inexpensive.
It’s so much more than just an “adapter”, as written on the packaging – it’s a fairly smart sound card with a built-in DAC, ADC, automatic detection of if anything is plugged into it, and even supports in-line remote control commands. And it’s remarkable how small it is with all of these features and technology built into it.
Rather decent unboxing experience (for the price); very nicely and cleanly designed packaging that can also be used as a carrying case (since there is no other included pouch or case other than the cardboard packaging itself).
Small.
Clean design.
White.
No Apple logo on it – the only sign that it’s made by Apple (aside from its design, but other companies have subsequently manufactured comparable-looking small DACs) is the faint grey text on the cable.
While the USB-C plug (that most likely contains the electronics) and multi-purpose 3.5 mm socket appear to be well-made, the cable between them, while fairly soft and nicely flexible, doesn’t appear sturdy or durable at all but pretty fragile instead.
Surprisingly, it supports three-button in-line remote control commands (volume up, play/pause, volume down) when used with my Windows 10 computer.
What’s definitely nice: it can be basically left plugged in all the time, as it automatically senses if anything is plugged into it and accordingly adjusts its features. If nothing is plugged in, the output is disabled automatically and it doesn’t even show up in the Windows sound menu anymore but will show up again and is selected automatically once something is plugged into it.
Sound:
My ZOTAC ZBOX CI547 nano running Windows 10 Pro 64 Bit is the only source that I’m using.
I’m only using my Apple USB-C DAC purely as a DAC for in-ears and headphones, and haven’t tested its ADC capabilities yet.
Volume Control:
Logically, the volume is controlled by Windows’ system-wide standard 100 attenuation steps (plus mute). Unfortunately, even the quietest possible volume setting above mute (≙”1”) is much too loud for me, so I need to further lower the volume in foobar2000 and YouTube drastically.
Frequency Response (no Load):
Nor real surprise; it’s flat and therefore exactly as it should be.
Output Impedance (complex Load Frequency Response/Frequency Response Deviation with my Ultimate Ears Triple.Fi 10 as complex Multi-BA Load):
Based on the frequency response deviation, the Apple DAC’s output impedance is around only 0.3 Ohms, which is truly excellent.
Hiss Performance:
Using my near-extremely sensitive Shure SE846, there is only the tiniest bit of barely perceptible hiss when no music is playing or when an empty audio file is played.
When used with my Ostry KC06A that is even a bit more sensitive, the amount of audible hiss in quiet passages and empty audio files or when nothing is played is very little and close to being inaudible.
Using my extremely sensitive Campfire Audio Andromeda that is the most sensitive out of the three, the audible hiss is still very little, which makes the Apple USB-C DAC an amazing performer in terms of hiss performance with very and/or extremely sensitive in-ears.
As for comparisons, it even slightly surpasses my iBasso DX90, is only beat by my RME ADI-2 DAC and Leckerton Audio UHA-6S.MkII, and audibly outperforms the FiiO Q5 with attached AM1 module or my Chord Electronics Mojo.
(On a side-note, though, when used with my Campfire Audio Andromeda, and only with my Campfire Audio Andromeda, I can clearly and constantly hear pops and crackles during playback that sound like continuously appearing electric shocks (i.e. when the DAC’s output is deactivated, because when there’s no audio signal for some time, it disables/disconnects the output (it’s still active and listed on the computer, but there is no more audible hiss and no pops and crackles, which means that the audio output is deactivated)), but as soon as I touch a metallic surface of a device that is also connected to the same electric supply mains, the pops and crackles disappear, which could mean that there’s perhaps (actually most likely) some grounding issue where I live, and it becomes audible with my extremely sensitive Campfire Audio Andromeda.
Okay, yup it really seems like it had been a grounding issue, as unplugging the power cord from my RGB light strip’s power supply resolved the issue and the crackles and pops disappeared (whereas there was even more, additional and even nastier noise when the RGB light strip was turned on (it was turned off but plugged in before)) and now there are absolutely no pops or crackles or any other abnormal noise even with my Campfire Audio Andromeda (which leads to the conclusion and insight that as the Apple USB-C DAC doesn’t have its own power supply but is dependent on the source’s, it is more prone to picking up any power mains/supply-induced noise than (most) battery-powered devices (such as the FiiO Q5 that has never emitted my RGB LED strip power supply-induced noise through my Campfire Audio Andromeda)).)
Subjective Sound Perception:
Neutral, clear, clean and very precise. Basically as audibly transparent, good-sounding and clean-sounding to my ears as it gets.
Precise and tight bass reproduction with sensitive multi-BA in-ears.
Subjectively large and very accurate soundstage; slightly on the oval side.
Seriously, there’s absolutely no subjective sonic fault that I could find, regardless of price.
In other words, excellent transparent performance regardless of price. There is absolutely no reason at all to pay more for a USB DAC, at least purely based on sound quality with headphones.
Conclusion:
Very affordably priced but without any compromise in terms of sound quality that is very good regardless of price – but unfortunately, the lowest possible volume setting (in Windows 10) is too loud for me. The cable doesn’t really appear very durable, though.
Aside from features and stuff (build quality, inputs and outputs, power output, …), purely based on the objective sonic performance, there is absolutely no reason to buy any other USB DAC for headphones. Perfectly neutral sound output, very low output impedance, very good hiss performance.