Introduction

This is the second in a series of FiiO products being covered on TechPowerUp, with the first the FiiO FA7s set of all balanced armature driver in-ear monitors. I mentioned in said review how FiiO puts out more products in a year than most companies do in a decade, and FiiO not only has multiple lines of IEMs, but various sources to drive them in the form of digital audio players and DAC/amp combo units. We have previously taken a look at two separate FiiO portable DAC/amps, covering both wired and wireless options, and now examine a desktop class unit in the same realm.


The FiiO K5 Pro ESS is a forced iterative release due to the AKM factory fire of 2019, which resulted in a massive shortage of digital-to-analog converter chipsets from arguably the biggest manufacturer of said chipsets at the time. ESS quickly saw growth opportunities galore and expanded its Sabre DAC line to cater to the demands of all of AKM's customers left helpless for future plans. As the name suggests, the K5 Pro ESS uses an ESS DAC and is otherwise similar to the older K5 Pro desktop DAC/amplifier that distinguishes itself from the portable class by necessitating AC mains as opposed to USB power. The original plan was to combine coverage of the K5 Pro ESS with the FiiO FA7s IEMs akin to the FD3 and New K3 from before, but it quickly became obvious that the FiiO K5 Pro ESS is worthy of its own article. Then another FiiO item came along and bumped the K5 Pro ESS off a dedicated review slot, so we are at it with a detailed quick look article instead! Let's thank FiiO for providing TechPowerUp a sample as we begin with a look at the product specifications in the table below.

Packaging and Accessories

I could write a whole page dedicated to FiiO's packaging and it would still fall short, such is the nature of the great first impression FiiO products leave. The K5 Pro ESS comes in a thick cardboard box with a black base and glossy iridescent printing that changes color depending on the viewing angle and that of incident light. On the front is the company logo and product name along with an outline of the product and its salient marketing features. Some basic specifications are on the back, accompanied by contact information for FiiO and an interesting note about the product likely going to be upgraded—I don't know whether this was before the K5 Pro ESS was even a thing outside of that label on the bottom. Side flaps on top can be unfurled to access the contents inside, with the K5 Pro ESS safely placed between two shaped foam sheets, a handy user manual on top (online copy here), and the other accessories inside a separate smaller cardboard box at the bottom.


I mentioned that the FiiO K5 Pro ESS is a desktop class source, and with it comes a two-piece AC mains power adapter and power supply that accepts 100–240 V and up to 0.55 A while providing up to 22.5 W on the 15 VDC rail. Additionally, you need a USB connection to make the most of the product as an actual DAC, and FiiO provides a 3' long Type-A to type-B cable, no doubt for a USB type-B port on the K5 Pro ESS itself. A warranty card completes the paperwork, and we then see a 3.5 mm to 6.35 mm (1/4") single-ended adapter to convert IEM/portable headphone cables to the larger output on the FiiO K5 Pro ESS. Rounding off the unboxing section is a dust cover for an optical input, and a set of four circular rubber feet.

Closer Look

Having recently used the FiiO New K3 for a couple of IEM reviews, I went in expecting an aluminium alloy enclosure in a matte black finish that feels and looks cool in person. I still was not expecting the K5 Pro ESS to be that much larger at 120 x 146 x 55 mm and weighing nearly 500 grams. This is a solid-feeling chunk of metal, which is reassuring in a manner that doesn't mean much by itself, but is good nonetheless. The design language is clean, with tasteful branding on the top and the Hi-Res Audio logo showing up twice. Smooth, rounded corners greet us, as well as a front fascia that distinctly curves outwards for some glitz to an otherwise monochrome design. On the front, from left to right, is an input selector switch (1- USB, 2- Line in, 3-SPDIF/optical) alongside another switch for low to medium to high gain via an increasing number of filled dots. These are steel switches with good tactility and no room for ambiguity on where they land. The center is occupied by a relatively large volume knob that also acts as an on/off switch at the starting position, and there is a painted-over line to show current positioning. Then comes the expected 1/4" (6.35 mm) single-ended headphone output on the right, and as shall be seen later on, an indicator light is associated with the volume knob.


Various supported inputs on the back are neatly labeled as such, with the numbers corresponding to the three on the input selector switch of the front. Going from left to right, we get a choice of either Coaxial or S/PDIF for a digital signal to the output, corresponding two-channel line in and line out RCA ports in white (left) and red (right), and the undoubtedly more often used USB Type-B input to use the FiiO K5 Pro ESS as a proper desktop source—the more relevant application for TechPowerUp readers. The power jack is all the way to the right, and further branding and certification information is on the top and bottom alike. An examination of the bottom reveals four pre-installed rubber pads that raise the K5 Pro ESS off the desk to prevent scratches to the metal chassis while adding friction against the desk, so the provided replacement feet in the box could be used when the pre-installed ones wear out or to lay the K5 Pro ESS on the side if desk space is limited.


At this point, I was about to show you some photos of the insides of the K5 Pro ESS—after all testing had been finished, of course. However, a single stripped screw head destroyed that endeavor. Instead, I decided to treat you to a family photo session of the FiiO K-series of products I have on hand, including the portable New K3 we saw before, this K5 Pro ESS, and the newer K9 Pro ESS, which will have its own full review and is why the K5 Pro ESS got a quick look article instead. If you were wondering what makes this a K5 Pro ESS and what happened to the K5 and K5 Pro, I'll refer you to this handy FAQs section that describes the exact differences between these models. In summary, the K5 Pro with an AKM AK4493 DAC added some more features and fully replaced the older K5, and the newer K5 Pro ESS has the ES9038Q2M DAC with slightly better performance. Note how the K5 Pro ESS stacks up in the middle of the three quite well in both size, mass, I/O options, and no doubt cost!