FiiO M21 Digital Audio Player

The FiiO M21 redefines the entry-level Android music player with flagship lineage: four Cirrus Logic CS43198 DACs in an eight-channel fully differential design, a two-stage amplifier delivering up to 950mW per channel, and a 6nm Snapdragon 680 running Android 13 for your streaming apps, all in a compact aluminium body with a 4.7-inch screen. FiiO’s patented desktop mode protects the battery at home, a 4,000mAh battery gives up to 15 hours on the move, and an optional cassette case turns it into a retro Walkman. It won Headfonics’ Best DAP 2025 (Bang for Buck) and a VGP 2025 Summer award.

Four CS43198 DACs, fully balanced

Four DAC chips make an eight-channel fully differential output, for class-defying dynamics and strong resistance to interference. The amplifier works in two stages: OPA1692 op-amps handle voltage amplification and SGM8262s current amplification, with a high-precision impedance-matching network between DACs and amplifiers, for purer sound with rich detail: up to 126dB signal-to-noise, a 1.6µV noise floor and distortion as low as 0.0003%.

Desktop mode and super high gain

Desktop mode appears on an entry-level FiiO player for the first time (patent ZL202321946664.8): switch it on with USB power connected and the M21 runs entirely from the external supply, so the battery is neither charged nor discharged and doesn’t wear out on your desk (below 15% it charges anyway). Connect a PD 2.0 or 3.0 adapter to the POWER IN port and you can select super high gain, which switches to a higher-voltage supply with a 21V peak-to-peak swing: 950mW per channel into 32Ω balanced, desktop-level power for a wider range of headphones. On battery, high gain still gives 720mW balanced and 290mW single-ended.

Flagship-grade power and parts

Separate power paths for the digital and analogue circuits reduce crosstalk, and the analogue side is divided further into independent supplies for the DACs and amplifiers, for a wider dynamic range and more natural detail. The digital and amplifier sections sit in separate shielded compartments. High-precision thin-film resistors and low-drift capacitors keep the channels consistent, and more than ten low-impedance, high-capacity tantalum capacitors give the DAC and amplifier plenty of energy in reserve.

FPGA and femtosecond clocks: no resampling

A fifth-generation FPGA with two custom crystal oscillators, screened to femtosecond-level standards, provides a precise, low-jitter clock that matches PCM and DSD at every sample rate. Every app plays at its original sample rate, with a global 10-band PEQ and an All-to-DSD option. Formats run to PCM 384kHz/32-bit, native DSD256 and full MQA 8x unfolding.

Smooth Android 13

The octa-core Snapdragon 680, made on a 6nm process with cores up to 2.4GHz, uses less power than chips in rival players and keeps Android 13 smooth, with 4GB of RAM and 64GB of storage (about 52GB free) plus microSD up to 2TB. Five modes cover Android, Pure Music, Bluetooth receiver, USB DAC and AirPlay, and a customisable multi-function key can add favourites, play/pause, switch filters or EQ, jump to USB DAC or Bluetooth mode and more. Two-way Bluetooth 5.0 sends LDAC, LHDC, aptX HD, aptX, AAC and SBC and receives LDAC, AAC and SBC.

Back to the Walkman era

Fit the cassette-style case (sold separately) and the M21 switches to a retro tape interface with vintage sound effects; touch is disabled in the case, so you control it with the buttons. Take the case off to return to the normal system. The M21 also docks in FiiO’s RETRO BOX speaker.

Outputs for any setup

The 3.5mm and 4.4mm sockets are headphone outputs and, with their own line amplification, line outputs for active speakers or amplifiers; the 3.5mm also gives a low-jitter coaxial output (jitter 70% lower, up to 384kHz/24-bit and DSD128). USB audio output turns the M21 into a streaming transport for an external DAC. Only one headphone output works at a time.

15 hours and 20W fast charging

The 4,000mAh high-voltage battery lasts up to 15 hours single-ended (12.5 hours balanced) and charges in about 1.5 hours with 20W PD fast charging. Of the two USB-C ports, only POWER IN supports fast charging and desktop mode; the USB 3.0 port handles data, USB host and OTG.

True quality, inside and out

The all-aluminium body has a frosted AG glass back with a fine texture and a comfortable grip, and the 4.7-inch fully laminated screen has an oleophobic coating against fingerprints. RGB lights pulse with your music.

Good to know

• FiiO Link lets you control the M21’s FiiO Music app from your phone: over Wi-Fi or Bluetooth from Android, over Wi-Fi from an iPhone.
• Dock it in the FiiO RETRO BOX speaker, or protect it with the leather case or cassette-style case.
• For a smaller budget, see the FiiO JM21.
• In the box: M21, screen protector (fitted), protective case in a matching colour, USB cable and quick start guide.