K15

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Sonoma 14), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Singxer SU-6 USB bridge, LHY Audio SW-8 & SW-6 switch, Sonnet Pasithea, Laiv Audio Harmony; Active filter: Lifesaver Audio Gradient Box 2; Power amplifiers: Vinshine Audio x Kinki Studio Dazzle & Gold Note PA-10 Evo in mono on subwoofer; Headamp: Enleum AMP-23R; Phones: Raal 1995 Immanis; Loudspeakers: Qualio IQ [on loan] Cables: Exact Express Flame, Furutech; Power delivery: 2 x Kinki/Vinshine Tai Hang on amps and source stack, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, AudioQuest FogLifters; Room: 6 x 8m with open door behind listening seat; Room treatment: 2 x PSI Audio AVAA C214 active bass traps
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe with POW; Preamp/filter: Lifesaver Audio Gradient Box 2; Amplifier: Kinki Studio EX-B7 monos; Loudspeakers: Virtual Hifi Cobra [on loan]; Subwoofer: Zu Method; Cable loom: Exact Express Earth; Power delivery: Vibex Granada/Alhambra, Akiko Audio Corelli Corundum & Castello Solo; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Furutech cable lifts, Furutech NFC Clear Lines; Room: ~3.5 x 8m
2nd headfi system: DAC: Cen.Grand DSDAC 1.0 Deluxe with POW; Headamp: Cen.Grand Silver Fox; Headphones: Raal 1995 Magna, HifiMan Susvara
Desktop system: Source: HP Z2 work station Win11/64; USB bridge: Singxer SU-2; DAC/preamp: COS Engineering D1; Headphone amp: Kinki Studio THR-1; Speaker amps: Topping B200 monos; Loudspeakers: Virtual Hifi Viper; Headphones: Final D-8000, aune SR7000, FiiO FT7
Upstairs headfi system: FiiO R7; Headphones: Meze 109 Pro, Fiio FT3
2nd upstairs speaker system: Source: FiiO R7; Integrated amplifier: Simon Audio Lab i5; Loudspeakers: ModalAkustik Musikboxx with Dynaudio S18 subwoofer
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: €599

"I feel embarrassed about how much love I've given FiiO this year. It looks like shilling when one brand keeps popping up in my coverage. But here's the thing: FiiO introduced over 40 new products in 2025. Forty. The Chinese company makes everything from dongle DACs to streaming DACs, from IEMs to over-ear headphones, all targeting cash-strapped audio enthusiasts who refuse to accept that good sound requires deep pockets. They even offer a mechanical keyboard with an internal headphone amplifier. More importantly, their hit-to-miss ratio is unusually high. When they get it right—and they often do—they get it really right." That was John Darko on why FiiO's FT7 planarmagnetic headphones figure on his 3-short list of 2025's Expectation Recalibrators. By then that headphone had already occupied my own 6-short list of 2025's Favourite Finds. Great minds or perhaps ears 'n' all? With only a week left on the year, my factory contact Huang Fufeng with the easy Western call name Yellow spotted a last-minute op to ride the same wave before it crashed. Could I review their K15 desktop deck pulling triple duty on RCA/XLR preamplitude, 3wpc/32Ω headphones and DACitude with proper dual-mono AKM AK4497SVQ attitude? For reasons unfolding below, I said yes. Before your inner Snooty predicts basic opamp gain, swallow these eight helpings of discrete ON Semi bipolar humble pie. And yes, OPA1642 opamps do figure in the voltage buffer/preamp stage preceding the NJW1195A four-channel volume control from Nisshinbo. Phew. That was a lot of alphanumeric salad.

Next forget all about a solitary motherboard by Plain Jane or Simple Jack. The K15 runs a mother, father and daughter board via these digital, analog and PSU assemblies. Apartheid pursues reduced interference for lower noise. Whilst this 30W power supply is a 100-270VAC switcher of 12V/2.5A output rated for five million (!) hours running 14 low-dropout linear regulators, the K15 can also accept an external DC feed for those preferring linear power of their own choice. The DAC's crystal oscillators are AS318-L Accusilicon, USB is handled by XMOS, the multi-core processor is an Ingenic X2000, the 32-bit MCU an Xtensa LX7 dual-core with 240MHz clock speed. The alphanumerical salad bar was open for a refill.

Digital | analog | power

There's a 10-band parametric EQ to massage headphone response curves using FiiO's software interface via the control app or RS232 USB connection to a PC. [Apple's Safari browser can't open the PEQ page so use a Google-based browser like Edge or Chrome instead.] Another 10 curves are pre-coded so not modifiable. EQ won't work on the analog RCA and 4.4mm inputs presumably because those don't get digitized. File support is up to 32/768, DSD512 and MQA x 8. Bluetooth via QCC5125 chip supports version 5.1. However, the K15 sadly has no DLNA/UPnP. Cover jpg up to 1.2MB must embed in a track's file to display. Other formats or external covers won't show. Digital filter options span six and we can set max volume and l/r balance.

Screen shot of PEQ webpage. Use mouse-over loupe to zoom in; or right-click to view at full size in a new window.

There's Gigabit LAN with RoonReady and AirPlay, 2.4/5G WiFi plus classic IR remote. HeadFi has five hardware gain settings from -12dB to +12dB and sub 1Ω output impedance. The 240×1'200px LCD display measures nearly 4 inches across. The line outputs in DAC/pre mode deliver 2.4/4.8Vrms on RCA/XLR. The back panel is self-explanatory. So is the need for a Windows USB driver.

As the next page shows, so is the ability to fly software-based VU meters. What may be less obvious unless you're a well-entrenched FiiO fan? €599 bags the lot. The phrasing was deliberate. What the K15 in its compact 25x21x6.7cm WxDxH 2.1kg silver or black shell can do is a lot. Save for perhaps blood-sucking affronts to civility so extreme vampire loads and their very hard-of-hearing handlers, that should include driving nearly all headphones. This accumulation of competence against a humbler sticker explains why I accepted Yellow's request. I can't be alone feeling impressed by these specs. Still, I dislike black so asked for a silver sample. Would the green leprechauns at Dublin customs smile upon my shipment? Or would they get all bristly with proof of payment demands to require FiiO's intercession on virtual letterhead to confirm a commercial sample on short-term loan? John Darko had three FiiO shipments which Berlin customs never released. Thus far Eire has responded favourably to remote benedictions by various senders. But clearly parcels entering the EU from outside are suddenly subject to more scrutiny. Has Trump's acute yellow fever infected our faraway shores? Fingers and ears crossed that the K15 will shortly ring my bell. Incidentally, the K17 in identical case work increases power to 4wpc/32Ω, expands to a 31-band PEQ hosted on an dedicated onboard DSP chip which the K15 omits, runs a 35-watt linear power supply, three clocks, higher-spec AKM chips and adds coaxial and Toslink outputs. The total of its extras adds €400 to today's bill. Sweet spot, anyone?