FiiO M17 Flagship Portable High-Resolution Digital Audio Player (Missing all cables and stand)

The FiiO M17 is FiiO’s portable desktop-class player: two ESS ES9038PRO DACs, THX AAA 788+ amplification and two power supplies, battery for the road and 12V DC for the desk, and up to 3,000mW per channel from its balanced outputs. It runs Android 10 on a Snapdragon 660, with a 5.99-inch screen, a 9,200mAh battery, four headphone sockets, coaxial in and out, Wi-Fi with AirPlay and Roon Ready, and two-way Bluetooth.

Desktop-class DACs and parts

Each audio channel has its own desktop-class, eight-channel ES9038PRO, so every channel has eight parallel outputs summed together, for higher resolution and very low distortion. Around them FiiO used parts more usual in desktop equipment:

• TI OPA2211 op-amps, with voltage noise as low as 1.1nV at 1kHz and THD+N of −136dB.
• A 470mF DMF supercapacitor, equal to 10,000 47µF tantalum capacitors, with an ESR of 45mΩ (15% of a tantalum capacitor’s), as a solid base for a large power supply.
• An LT3045 ultra-low-noise regulator (0.8µVrms from 10Hz to 100kHz) gives the DACs stable, clean power.
• NDK femtosecond oscillators provide one precise, low-jitter clock for the whole audio circuit.
• An XMOS XUF208 USB receiver for low-latency USB DAC use up to 768kHz/32-bit and DSD512.

THX AAA 788+ and desktop gain

FiiO and THX developed the THX AAA 788+ together: an upgraded version of the original with 225% more output power, up to 3,000mW per channel, and a lower output impedance, so it drives all kinds of headphones with ease. On battery there are four gain levels: low, medium, high and over-ear headphone mode. On DC power an Enhanced over-ear headphone mode unlocks true desktop gain, up to 16dB from the balanced outputs.

The two power supplies matter. On DC the analogue circuit runs at 11.5V, 35% higher than on battery, and the battery is not used, which keeps it healthy. A BAT/DC switch chooses between them.

Built like a desktop

Inside are 17 immersion-gold circuit boards, with the analogue and digital sections on separate boards to reduce interference, and seven high-conductivity copper-alloy shields against electromagnetic noise. The design took a year and a half, six major iterations and twelve rounds of structural optimisation; stacking the boards with stainless-steel hexagons fits nearly twice the usual circuit-board area into the body. To handle the heat, FiiO used “H”-type heat dissipation, vapour-chamber liquid cooling and a 151g aluminium unibody frame that carries heat away. (FiiO’s fan cooling stand is not included with this unit.)

The CNC-machined aluminium unibody has sharp, mech-inspired lines. Volume is set by an analogue potentiometer knob or by buttons, through 120 steps either way, and a seven-colour RGB light on the knob and side can follow the audio (showing the Bluetooth codec, the file quality or the USB sample rate), the volume, the battery or the temperature, with the top and side lights set separately.

Android, streaming and connections

Open Android 10 runs streaming apps without sample-rate limits, on a Snapdragon 660 with 4GB of RAM and 64GB of storage (about 46GB free), plus a microSD slot for cards up to 2TB. USB 3.0 transfers files at up to 100MB/s, the 5.99-inch 1080 × 2160 screen turns automatically like a phone’s, and a Pure Music mode is there for playback alone. Wi-Fi brings DLNA, AirPlay, Wi-Fi music transfer and Roon Ready. A Qualcomm QCC5124 handles Bluetooth 5.0 both ways: the M17 sends LDAC, aptX HD, aptX, AAC and SBC to wireless headphones, and receives those plus aptX Adaptive and aptX Low Latency from a phone.

It works as an Android player, a USB DAC for a computer, a Bluetooth receiver, an AirPlay receiver and a coaxial decoder. The RCA socket decodes coaxial input up to 192kHz/24-bit and DSD64, or sends coaxial output up to 384kHz/24-bit and DSD128 to a desktop DAC, and a second USB-C port works as a USB host for drives. FiiO Music adds a 10-band parametric EQ, and an in-car mode switches the M17 on and off with the engine.

Good to know

• This open-box unit comes without its cables and its cooling stand, and has the full manufacturer warranty. You will need a USB-C cable to charge it, and a suitable 12V DC supply for full-power desktop use.
• Included: the M17 with its screen protector fitted, leather case, micro-SD ejector pin, aluminium dust plug and manual.
• Recommended headphone impedance: 16–150Ω single-ended, 16–300Ω balanced.