| Name/Model | JM21 |
| Hardware solution | Main controller: Qualcomm Snapdragon 680; DAC: CS43198*2; Amp: SGM8262*2 |
| Working mode | Android mode/Pure music mode/USB DAC mode/Bluetooth receiving mode |
| Color | Sky blue, Black |
| Weight | About 156g |
| Dimensions | About 120.7x68x13mm |
| Volume control | Physical button |
| Display | 4.7-inch (750x1334) bezel-less display |
| ROM/Usable storage | 32G ROM/22G ROM usable;64G ROM/52G ROM usable |
| Channel balance | L20~R20 (0.5dB per level) |
| Buttons | Power on/off*1; Volume button*2; Play/Pause*1; Previous track*1; Next track*1 |
| USB | Type-C USB2.0*1 (Charging/Data transfer) |
| Headphone output | Standard 3.5mm port |
| Balanced headphone output | Standard 4.4mm port |
| Coaxial output | Standard 3.5mm port (shared PO) |
| Line output | Shared 3.5mm+4.4mm ports |
| 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 |
| Firmware upgrade | Supports upgrading through local storage+microSD card+OTA |
| Operation method | Supports gesture, two-button and three-button operations |
| Power supply | Supports 5V/≥2A |
| Charging time | （3G+32G）About 2h (5V2A charger) （4G+64G）About 2.5h (5V2A charger) |
| Volume | 49 |
| Gain | High gain |
| Display status | OFF |
| Playing track and format | MP3 44kHz/16bit |
| EQ | OFF |
| Load | 32Ω |
