New K3 Desktop DAC/Amp

FiiO made the deliberate decision of only calling the updated K3 desktop amplifier the New K3, meaning the packaging does not reflect the change either. Indeed, the packaging is similar to the FD3, but in white. We have the FiiO logo and Hi-Res Audio mark on top, a render of the product below, and a note at the bottom confirming this is indeed the K3—a USB DAC and amplifier. On the back is another authenticity check sticker, contact information for FiiO, the same hilarious note as on the FD3, and the mass and dimensions for the K3 itself. The only way to know what is different with the new K3 is by looking at the bottom-right corner, where it reads "K3 ES9038Q2M," which tells us about the new DAC employed here. The box opens at the top, and inside is a white cardboard box with another single flap that finally helps reveal the contents inside. There is an accessory box at the top, a larger cardboard cutout below hosting the K3 inside a wax paper wrap, and the paperwork underneath.


Here we have a separate warranty card that goes over how to do the authenticity check. FiiO also includes a multi-language quick start guide that is quite useful because there are a few things to note about using the inputs and outputs. The accessory box has a USB Type-A to Type-C cable in addition to some sticky foam pads to help with a more permanent installation.


The FiiO K3 is new to me, and the New K3 uses the same design as the older K3. Confused? Complain to FiiO. Look, the thing to note is that the New K3 happened because of a serious shortage of the AKM AK4452 audio DAC used before, so FiiO decided to make a revision by switching to the ESS Sabre ES9038Q2M instead. Nothing else has changed, including the smaller form factor of 70×58×22 mm and weight of ~80 g. Not bad for what is a wired solution marketed for desktops since it's still easily portable enough. The casing is black anodized aluminium that is CNC-machined and sandblasted for a smooth finish. The FiiO logo is on the front at the bottom, and the Hi-Res Audio sticker makes a comeback on the top. On the back, we see more certification information in addition to finding out that USB 2.0 is sufficient to power and drive the K3. The body is also rounded like a flask of fine whiskey, though it soothes you through fine audio instead. We see the back house the input, and you have the expected Type-C connector you will use to connect to your PC. There are less typical use cases for outputs on the back, but between line out and coaxial out, there is the feasible option to drive less demanding speakers as well. Note the toggle switch to switch between USB Audio Class 1 and 2; if you are not familiar with these, Cambridge Audio has a decent primer here. In a nutshell, it defines the upper limit of audio playback from the source when it comes to bitrates, and you may want to switch to USB Class 1 if your system does not support it.


The front has both a single-ended 3.5 mm out and a balanced 2.5 mm out available. This too is unfortunately the same as for the older K3 even though FiiO recognizes that the 4.4 mm balanced output has surpassed the 2.5 mm one in popularity, so it would have really made the New K3 worthy of its own dedicated review had the company gone that route. I suppose I now do understand why it did not get a different name, such as "FiiO K3s," for instance. A bass switch and a gain switch are also present, with the former enabling a bass-heavy EQ on the outputs and the latter handy for more demanding headphones. But nothing truly grabs your eye as much as the combined power switch and volume wheel. A knurled finish at 45° to the plane of the knob makes volume control a breeze, combined with the click at the beginning when initiating power output before using the white marker for a visualization of the volume increase. An indicator LED next to the volume wheel also changes color depending on the source signal—blue for a sample rate under 48 kHz, yellow for above 48 kHz, and green for DSD (Direct Stream Digital).


At this point, I would talk more about the components inside and the capabilities of the FiiO K3, but then I noticed there were just two tiny Phillips head screws keeping me from taking a closer look inside. As such, after all testing was finished, I took a precision screwdriver to these screws on the back and pushed the inner assembly out through the front. This gives us a closer look at the body and the isolating points to ground the PCB itself.


I don't have the previous (current still at the time of writing) version of the FiiO K3, but looking at some disassembly photos online indicates an identical PCB structure aside from the changed USB DAC. We get two blue PCBs with average solder quality throughout, which is clearly nothing to worry about. One side hosts the XMOS U30881C10, the commercial variant of the XMOS XUF208 32-bit microcontroller handling the USB input, which in turn is capable of decoding up to 384 kHz/32-bit files and 256-bit DSD files natively. This converts USB audio into digital signals that are then passed onto the DAC.

This is the aforementioned change, with FiiO going with an ESS Sabre ES9038Q2M reference DAC over the previous AKM AK4452. This ESS Sabre DAC is flagship-class in the portable lineup, which means it's good but then again also not that good. ESS itself refers to it as a 32-bit stereo mobile audio DAC, and it can match the XMOS decoder in capabilities. What it does offer over the previous AKM DAC is a higher SNR of up to 129 dB from the previous 115 dB, and distortion also drops from the THD+N of -107 dB to -120dB. FiiO further states that the circuit design "has been optimized for a low noise floor and clean sound."

The amplifier section remains unchanged with the use of a Texas Instruments OPA1612 and dual TI OPA926. This can provide up to 2 Vrms on the line, which is fine for many consumer-class headphones and earphones, but I was left wanting more from what is still a wired-only solution. What that works out to is ~114 mW at 32 Ω on the 3.5 mm output and ~200 mW at 32 Ω with the balanced output that uses both OPA926 amps. It means that higher impedance headphones will need something more powerful, but higher current/lower impedance headphones will also need a different solution. To give you a better idea, the FiiO BTR5 Bluetooth DAC/amp can provide more power on the balanced output. What you do get is the line out on the back being powered directly by one of the OPA926 chips, which makes it a good line out for speakers and other 3.5 mm headphones within the power bracket, making the most of the reduced interference from other components in the pathway. Just remember not to plug any headphones into the other side if doing so since this OPA926 is pre-occupied already.


So while this New K3 may not be a truly versatile desktop USB DAC/amp, it can still power a lot of things, including the FiiO FD3. In fact, it is quite overkill in the amplifier section for the FD3 since it is an average set of IEMs for impedance (32 Ω), while high on sensitivity to where the DAC and a clean signal is more important. In that regard, the FiiO FD3 and New K3 work out quite well in combination. Just remember to start off low on the volume wheel and turn it up as needed. The FD3 Pro with changeable cable connectors also allows for a 2.5 mm TRRS plug option with the K3, which is all sorts of overkill. Note that for the best USB performance, you should download the FiiO ASIO drivers and enable the New K3 as the dedicated stream output in the media player of your choice. I will go over this in more detail in a subsequent FiiO DAC/amp review, so keep an eye out for that.