Fiio K3 USB DAC & Headphone Amplifier

Having spent most of my computing life on Macs, I’ve seldom felt the need for an external DAC/Amp combo to drive my headphones. At least as far as Single-Ended output is concerned, I’ve always thought MacBook Pros did a far better-than-average job of reproducing sound via their built-in 3.5mm stereo headphone jacks. I always had enough power to drive even pretty demanding headphones, and each time I tried a portable DAC/Amp, I would end up returning it, because I simply didn’t notice enough of an improvement to warrant the expense. If it ain’t broken, don’t fix it, right?

Then I found myself on the “Top of the Line” Dell XPS, and my jaw was practically in my lap most of the time I had headphones plugged in. “Are you kidding me?” I would ask, gobsmacked, “Is this really the best that one of the largest PC manufacturers on the planet can offer?? This sounds like dog shit!” Add in all the post-processing shenanigans and bloatware that Dell and some other shops use to “improve” their sub-par audio hardware, and you might find yourself banging your head on your desk, wondering why this is a lingering problem in the twenty-first century.

Needless to say, if you’re running a Windows-based (non-gaming) laptop, or you want to use high-impedance or balanced headphones, the stock hardware just isn’t going to cut it. PC manufacturers don’t consider audiophile-grade sound a priority, and the DAC/Amp circuitry in nearly every productivity-focused PC laptop on the market makes this abundantly clear. They all lack bass, they have piss poor high end resolution, and only enough power to drive cans under 100 ohms, and even then, just barely. So you owe it to yourself to try a portable DAC/Amp to get what your PC manufacturer is too cheap to give you, and to add balanced output capability to your Mac (if nothing else).

I’ve long been a fan of Fiio’s audio gear –they offer a lot of capability and connection variety at reasonable prices. I’ve owned a few of their Hi-Rez digital audio players over the years, and never found anything to complain about (save for the occasional gripe about their Android-powered UX experience). So the K3 External USB DAC/Amp was my first and only choice, and frankly, a no-brainer when I decided to sweeten my MacBook Pro’s audio output capability.

With a simple USB-C connection, you get 3.5mm TRS Single-Ended and 2.5mm TRRS Balanced outputs on the front, as well as 3.5mm TRS Single-Ended line level, and both Optical and Coaxial digital output from the back. It runs in both USB-1 and USB-2 class modes (the latter requires Fiio’s driver on a PC, but not on a Mac), and features both a two-level gain switch and bass boost switch, which seems to pull the mid-bass up a tad too much, and isn’t even necessary, IMO. The DAC is an ESS ES9038Q2M, fed by an XMOS USB receiver chip with dual crystal oscillators that easily handles up to 384KHz/32-bit and native DSD256 bitstreams. And the OPA1612 op-amp provides enough punch to drive everything in my arsenal, from the surprisingly mobile-friendly 32-Ohm Sivga P-II Planar Magnetics, all the way to the 300-Ohm Sennheiser HD 650.

The volume knob features a nice, continuous smooth turn with a satisfying on/off click, and the LED indicator on the front changes color to indicate the sample rate being received –blue for 44.1 or 48KHz, Yellow above 48KHz, and Green when receiving DSD bitstreams. This last bit is imperative to me, as I found my Dell (and pretty much any PC running Windows 11) would simply ignore my audio software’s rate-switching preferences and dump 44.1KHz to any outboard hardware, no matter the source material. I like to see some kind of feedback from the outboard device itself, telling me it is in fact getting what I’m trying to send to it.

Included in the box is a 3′ USB to USB-C cable, so if you’re on a relatively new laptop and don’t want to use an adapter, I’d recommend just grabbing a 1′ C-to-C like this one.

As expected, the sound is crisp, clear, and substantial, with no noise whatsoever, and no coloration added (save for the aforementioned bass boost, if you decide to use it). I get more than enough volume on most <100 Ohm cans with the gain set to low, and haven’t exceeded 50% on the volume knob driving 300 Ohm cans with the gain set to high. It’s simply more power than I’m likely to need anytime soon.

I should also mention that the K3 does not feature an internal battery. Being USB Class 1 & 2 compliant, it derives its power from the connected PC, tablet, or mobile device. Just be advised that if you’re using it with a phone or tablet, it will drain your device’s battery faster.

One minor quibble about rate switching, and it’s really not even a ding against Fiio, because all USB audio devices and computers I’ve worked with seem to have this problem: There is a tiny drop-out if the sample rate has to change between the end of one track and the start of another. This tends to shave off the first half-second or so of a track, giving the impression of a rapid “fade-in.” I don’t know if this will ever be resolved. A USB receiver chip needs a few milliseconds of bitstream flowing in order to autodetect the appropriate clock speed, so it might just be a law of physics that we haven’t found a workaround for yet. Maybe one workaround is to make sure all your music tracks have at least a half-second of silence at the beginning, but that’s not very practical. Again, it only happens if the internal clock has to adjust for a different sample rate between tracks; if you’re just playing tracks with identical sample rates back-to-back, there is no dropout. The K3 will stay in its last-used sample rate until told to switch lanes.