| 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/Black |
| 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 |
| Channel balance | L20~R20 (0.5dB per level) |
| 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 |
| 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 |
| Power supply | Supports D2.0 and PD3.0 fast charging |
