| General Specifications | 
		
		
			| Name/Model | 
			M21 | 
			Hardware solution | 
			SoC: Qualcomm Snapdragon 680, DAC: CS43198*4, Amp: OPA1692*2+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 | 
		
		
			| Memory card | 
			Single microSD card expansion, up to 2TB in theory | 
			BAL: 8~350Ω | 
		
		
			| Channel balance | 
			L20~R20 (0.5dB per level) | 
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			| Buttons and Ports | 
		
		
			| Buttons | 
			Power button*1; Multifunction button*1; Volume button*2; Play/Pause button*1; Previous track*1; Next track*1 | 
			USB | 
			Type-C USB3.0*1 (charging/data transmission)+Type-C POWER IN*1 (charging/independent power supply port) | 
		
		
			| Toggle switch | 
			HOLD switch*1; D.MODE switch*1 | 
			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 | 
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			  | 
		
		
			| Special functions | 
		
		
			| WiFi | 
			2.4GHz/5GHz, supports DLNA, AirPlay, WiFi song transfer, 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) | 
			Firmware upgrade | 
			Supports upgrade from local storage/memory card/OTA | 
		
		
			| Local decoding: Supports up to 384kHz/32bit; DSD256 (Native) | 
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			  | 
		
		
			| USB Audio: 768kHz/32bit; DSD512 (supports DoP/D2P/Native) | 
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			| Coaxial output: Supports up to 384kHz/24bit; DSD128 (DOP) | 
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			| 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%) | 
			Output impedance | 
			<1Ω | 
		
		
			| L+R≥405mW+405mW (32Ω, THD+N<1%) | 
			Crosstalk | 
			≥74dB | 
		
		
			| L+R≥45mW+45mW (300Ω, THD+N<1%) | 
			Peak output voltage | 
			10.6Vp-p | 
		
		
			| SNR | 
			≥124dB (A-weighted) | 
			THD+N | 
			<0.0003% (1kHz/-4dB@32Ω) | 
		
		
			| Frequency response | 
			20Hz~85kHz: attenuation<2dB | 
			Noise floor | 
			<2uV (A-weighted) | 
		
		
			| 20Hz~20KHz: attenuation<0.02dB | 
			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%) | 
			Output impedance | 
			<1Ω | 
		
		
			| L+R≥290mW+290mW (32Ω, THD+N<1%) | 
			Crosstalk | 
			≥74dB | 
		
		
			| L+R≥35mW+35mW (300Ω, THD+N<1%) | 
			Peak output voltage | 
			9.5Vp-p | 
		
		
			| SNR | 
			≥123dB (A-weighted) | 
			THD+N | 
			<0.0004% (1kHz/-4dB@32Ω) | 
		
		
			| Frequency response | 
			20Hz~85kHz: attenuation<2dB | 
			Noise floor | 
			<2.1uV (A-weighted) | 
		
		
			| 20Hz~20KHz: attenuation<0.02dB | 
			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 | 
			Line output level | 
			1.9Vrms | 
		
		
			| 20Hz~20KHz: attenuation<0.02dB | 
			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%) | 
			Output impedance | 
			<1.5Ω | 
		
		
			| L+R≥950mW+950mW (32Ω, THD+N<1%) | 
			Crosstalk | 
			≥109dB | 
		
		
			| L+R≥185mW+185mW (300Ω, THD+N<1%) | 
			Peak output voltage | 
			21.2Vp-p | 
		
		
			| SNR | 
			≥126dB (A-weighted) | 
			THD+N | 
			<0.0005% (1kHz/-12dB@32Ω) | 
		
		
			| Frequency response | 
			20Hz~85kHz: attenuation<2dB | 
			Noise floor | 
			<2.7uV (A-weighted) | 
		
		
			| 20Hz~20KHz: attenuation<0.03dB | 
			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%) | 
			Output impedance | 
			<1.5Ω | 
		
		
			| L+R≥720mW+720mW (32Ω, THD+N<1%) | 
			Crosstalk | 
			≥109dB | 
		
		
			| L+R≥90mW+90mW (300Ω, THD+N<1%) | 
			Peak output voltage | 
			15Vp-p | 
		
		
			| SNR | 
			≥125dB (A-weighted) | 
			THD+N | 
			<0.0005% (1kHz/-8dB@32Ω) | 
		
		
			| Frequency response | 
			20Hz~85kHz: attenuation<2dB | 
			Noise floor | 
			<2.7uV (A-weighted) | 
		
		
			| 20Hz~20KHz: attenuation<0.03dB | 
			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 | 
			Line output level | 
			3.9Vrms | 
		
		
			| 20Hz~20KHz: attenuation<0.02dB | 
			Dynamic range | 
			≥125dB (A-weighted) |