Closer Examination

The FiiO K7 is a desktop class DAC/headphone amplifier all-in-one device, akin to some others we have seen before. Indeed, it looks quite a lot like the FiiO K5 Pro ESS we saw before but is slightly larger at 120 x 168 x 55 mm while also being heavier at 610 g. This is a solid-feeling chunk of matte black aluminium alloy, which is reassuring in a manner that doesn't mean much by itself, but is good nonetheless. The design language is clean and relatable to the rest of FiiO's lineup, with tasteful branding on the top and the Hi-Res Audio logo showing up alongside the THX technology logo. Smooth, rounded corners greet us, as well as a front fascia that distinctly curves outwards, adding some glitz to an otherwise monochrome design. There is no display here as with some of the TOPPING and S.M.S.L. gear we've seen before, instead FiiO going for steel switches with good tactility and no room for ambiguity on where they land. Going from left to right, there is an input selector button that toggles through the four options listed above, having a white indicator LED associated with each. The first of the two switches control the gain (low/high) although FiiO doesn't mention what the SPL offset is between the two. Then we get a dedicated output selector switch allowing you to choose between PO (headphone out), preamp, and LO (line out). The center is occupied by a relatively large volume knob that is tied to a potentiometer while also being an on/off switch at the starting position, and there is a painted-over line to show current positioning. Note also the plastic diffuser ring around it that we will get to shortly. Then comes the expected 1/4" (6.35 mm) single-ended headphone output on the right, to go with a 4.4 mm balanced connector that I am happy to see given how popular it's becoming with more and more headphones and IEMs cables supporting it over other balanced options (XLR/2.5 mm TRRS etc).


There isn't much of note on the sides, FiiO having gone with a completely closed-off and curved metal chassis rather than having any vents for cooling. Then we get to the back where things get busy while still being labeled and arranged neatly enough to avoid confusion. Going from left to right we get RCA inputs (line in) should you wish to use this with another DAC, and then come two RCA outputs for preamp/line out to do the other way round whereby you just use the DAC section with/without volume control over the analog component downstream. There are three other inputs for the K7 in the form of optical, coax, and the expected USB input itself. Unfortunately FiiO continues to use a Type-B connector here rather than the newer Type-C we've seen on the more expensive K9 Pro ESS and Q7. This could just be a budget thing where FiiO simply has tons of these connectors on hand. Rounding off the tour here is the expected power input with FiiO having combined the on/off switch with the volume wheel up front.


An examination of the bottom reveals four pre-installed rubber pads that raise the K7 off the desk to prevent scratches to the metal chassis, while adding friction against the desk. Interestingly we don't find replacement feet in the product box as was the case with the K5 Pro ESS before. At this point, and after all testing was completed, I wanted to see whether disassembly is possible to get a closer look at the hardware inside. It starts off easy enough with seven Phillips head screws on the back panel that help remove it completely. But then the various soldered connectors and the volume wheel up front prevent the PCB from easily sliding out of the chassis to where all I could do here was get a few close-ups of the I/O plugs on the back as well as the various capacitors on the underside. Note also the finned heatsink used, to where FiiO could have perhaps gone with vents on the side to aid with heat transfer but decided the K7 does not get hot enough to merit them, unlike the K9 Pro ESS.


Thankfully FiiO comes to the rescue again in providing details about what makes the K7 tick, including two Asahi Kasei Microdevices AK4493SEQ 32-bit stereo DACs, an XMOS XU208 USB controller, and then some of the K9 Pro DNA is shared here courtesy two THX AAA 788+ linear amplifiers as well as two Nisshinbo Micro Device NJU72315 volume ICs. I will say that the volume pot used here isn't the smoothest in that I noticed the volume control with the knob has a dead zone early on, and then jumps in a more logarithmic manner rather than a smoother, more continuous approach even with analog inputs—this is down to the volume encoder and its implementation, perhaps FiiO could have gone with a different approach given this results in a reduced control range. All these provide excellent numbers for a more affordable audio source, be it the THD+N of <0.0003%, SNR of 125 dB, SNR of 120-128 dB, and crosstalk of >77 dB off the single-ended 6.35 mm output with the equivalent numbers being <0.0003%, 120-128 dB, and >124 dB off the balanced 4.4 mm output. The XMOS XU208 is an older platform but one that won't be a bottleneck for the price range the K7 operates in. If anything, the FiiO K7 just shows how the K9 Pro ESS got away with the same older hardware at a higher cost where the DACs contributed to a larger fraction of the component cost. There is no wireless connectivity on offer here, but overall I am pleased with the increased I/O functionality and the "better" hardware relative to the K5 Pro ESS as well as most other sources on the market in the $200 price range the FiiO K7 belongs to.