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FiiO M21 Digital Audio Player Specifications

General Specifications

Name/Model	M21	Hardware solution	SoC: Qualcomm Snapdragon 680, DAC: CS431984, Amp: OPA16922+SGM8262-2*2
Working mode	Android/Pure music/AirPlay/USB DAC/Bluetooth Receiving	Color	Titanium gold/Dark blue
Weight	About 193g	Dimensions	About 68x121x17mm
Volume control type	Button control	Display	4.7-inch (750x1334) bezel-less screen
Internal storage/available capacity (ROM)	64GB/About 52GB	RAM	4GB
Adaptive impedance	PO: 8~350Ω, BAL: 8~350Ω	Memory card	Single microSD card expansion, up to 2TB in theory
Channel balance	L20~R20 (0.5dB per level)

Buttons and Ports

Buttons	Power button1; Multifunction button1; Volume button2; Play/Pause button1; Previous track1; Next track1	USB	Type-C USB3.01 (charging/data transmission)+Type-C POWER IN1 (charging/independent power supply port)
Toggle switch	HOLD switch1; D.MODE switch1	Headphone out	Standard 3.5mm
Line output	Standard 3.5mm (shared PO)	BAL headphone out	Standard 4.4mm
BAL line output	Standard 4.4mm (shared BAL)	COAX headphone out	Standard 3.5mm (shared PO)
Exposed contacts	Connect to cassette-style protective case

Special Functions

WiFi	2.4GHz/5GHz, supports DLNA, AirPlay, WiFi song transfer, Roon Ready, etc.	Bluetooth transmission (5.0)	AAC/SBC/aptX/aptX HD/LDAC/LHDC
Bluetooth reception (5.0)	SBC/AAC/LDAC	FIIO Link	Android supports WiFi and Bluetooth control, iOS supports Bluetooth control
MQA	Supports MQA full decoding	ALL TO DSD	Supported
EQ adjustment	10-band dynamic EQ adjustment (±12dB), built in 8 types of preset EQ, self-define EQ	System navigation mode	Supports gesture navigation, 2-button navigation and 3-button navigation
Double tap to wake up	Supported	Power off timers	Supports Sleep/Idle power off
Max supported sampling rate	USB DAC: Supports up to 384kHz/32bit; DSD256 (Native) Local decoding: Supports up to 384kHz/32bit; DSD256 (Native) USB Audio: 768kHz/32bit; DSD512 (supports DoP/D2P/Native) Coaxial output: Supports up to 384kHz/24bit; DSD128 (DOP)	Firmware upgrade	Supports upgrade from local storage/memory card/OTA

Power Supply Parameters

Power supply	Supports D2.0 and PD3.0 fast charging	Charging time	About 1.5h (PD3.0 fast charging mode)
Battery life and test conditions:
3.5mm headphone out: 15 hours	Volume level: 44, Gain level: High gain, Display status: OFF, Playing track and format: MP3 44kHz/16bit, EQ: OFF, Load: 32Ω
4.4mm headphone out: 12.5 hours	Volume level: 33, Gain level: High gain, Display status: OFF, Playing track and format: MP3 44kHz/16bit, EQ: OFF, Load: 32Ω

Audio Parameters

Parts of performance and parameters of PO (3.5mm, USB DAC, Super High Gain mode)

Output power	L+R≥480mW+480mW (16Ω, THD+N < 1%) L+R≥405mW+405mW (32Ω, THD+N < 1%) L+R≥45mW+45mW (300Ω, THD+N < 1%)	Output impedance	< 1Ω
Crosstalk	≥74dB	Peak output voltage	10.6Vp-p
SNR	≥124dB (A-weighted)	THD+N	< 0.0003% (1kHz/-4dB@32Ω)
Frequency response	20Hz~85kHz: attenuation < 2dB 20Hz~20KHz: attenuation < 0.02dB	Noise floor	< 2uV (A-weighted)
Dynamic range	≥124dB (A-weighted)

Parts of performance and parameters of PO (3.5mm, USB DAC, High Gain mode)

Output power	L+R≥380mW+380mW (16Ω, THD+N < 1%) L+R≥290mW+290mW (32Ω, THD+N < 1%) L+R≥35mW+35mW (300Ω, THD+N < 1%)	Output impedance	< 1Ω
Crosstalk	≥74dB	Peak output voltage	9.5Vp-p
SNR	≥123dB (A-weighted)	THD+N	< 0.0004% (1kHz/-4dB@32Ω)
Frequency response	20Hz~85kHz: attenuation < 2dB 20Hz~20KHz: attenuation < 0.02dB	Noise floor	< 2.1uV (A-weighted)
Dynamic range	≥123dB (A-weighted)

Parts of performance and parameters of LO

THD+N	< 0.0005% (1kHz/-5dB@10KΩ)	SNR	≥122dB (A-weighted)
Crosstalk	≥111dB	Noise floor	< 1.6uV (A-weighted)
Frequency response	20Hz~85kHz: attenuation < 1.8dB 20Hz~20KHz: attenuation < 0.02dB	Line output level	1.9Vrms
Dynamic range	≥122dB (A-weighted)

Parts of performance and parameters of BAL headphone out (4.4mm, USB DAC, Super High Gain mode)

Output power	L+R≥540mW+540mW (16Ω, THD+N < 1%) L+R≥950mW+950mW (32Ω, THD+N < 1%) L+R≥185mW+185mW (300Ω, THD+N < 1%)	Output impedance	< 1.5Ω
Crosstalk	≥109dB	Peak output voltage	21.2Vp-p
SNR	≥126dB (A-weighted)	THD+N	< 0.0005% (1kHz/-12dB@32Ω)
Frequency response	20Hz~85kHz: attenuation < 2dB 20Hz~20KHz: attenuation < 0.03dB	Noise floor	< 2.7uV (A-weighted)
Dynamic range	≥125dB (A-weighted)

Parts of performance and parameters of BAL headphone out (4.4mm, USB DAC, High Gain mode)

Output power	L+R≥600mW+600mW (16Ω, THD+N < 1%) L+R≥720mW+720mW (32Ω, THD+N < 1%) L+R≥90mW+90mW (300Ω, THD+N < 1%)	Output impedance	< 1.5Ω
Crosstalk	≥109dB	Peak output voltage	15Vp-p
SNR	≥125dB (A-weighted)	THD+N	< 0.0005% (1kHz/-8dB@32Ω)
Frequency response	20Hz~85kHz: attenuation < 2dB 20Hz~20KHz: attenuation < 0.03dB	Noise floor	< 2.7uV (A-weighted)
Dynamic range	≥124dB (A-weighted)

Parts of performance and parameters of BAL LO

THD+N	< 0.0003% (1kHz/-0dB@10KΩ)	SNR	≥126dB (A-weighted)
Crosstalk	≥103dB	Noise floor	< 1.9uV (A-weighted)
Frequency response	20Hz~85kHz: attenuation < 1.8dB 20Hz~20KHz: attenuation < 0.02dB	Line output level	3.9Vrms
Dynamic range	≥125dB (A-weighted)

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