FiiO JM21: Portable Audio With Unusually Broad Reach

The FiiO JM21 is built around a useful idea: a dedicated music player can remain genuinely portable without being restricted to simple on-the-go playback. Measuring 120.7 x 68 x 13 mm and weighing approximately 156 g without a case, it combines a compact aluminum-alloy-and-plastic enclosure with a 4.7-inch HD touchscreen, Android 13, balanced amplification and several ways to connect with other audio equipment. Its $200 price places that broad functionality in an accessible part of the dedicated-player market. The result is a device intended not only for local music libraries and wired headphones, but also for streaming services, Bluetooth listening, USB DAC duties and integration with a separate digital audio system.

A portable design that remains practical

The JM21’s physical dimensions are central to its appeal. A thickness of 13 mm and weight of about 156 g make it substantially easier to carry than a full-size desktop source, while the 4.7-inch display provides a dedicated interface for browsing albums, managing playback and adjusting settings. Its 750 x 1334 resolution is suited to a compact music-focused screen rather than an oversized multimedia device.

FiiO uses a combination of aluminum alloy and plastic for the enclosure. This approach supports a balance between rigidity, manageable weight and everyday portability. The Qualcomm Snapdragon 680 processor is another pragmatic choice: it provides the computing platform for Android operation while being designed with power efficiency in mind. For an audio player, that matters because processor resources must support applications and wireless functions without unnecessarily compromising operating time.

Android 13 expands the player’s role

Android 13 allows the JM21 to run compatible music applications instead of limiting owners to a single playback ecosystem. Dual-band 2.4 GHz and 5 GHz Wi-Fi supports music streaming, while DLNA and AirPlay support provide additional ways to connect the player with networked audio environments. Owners can therefore combine locally stored files with online services and compatible network sources on one device.

The JM21 offers Android mode, pure music mode, USB DAC mode and Bluetooth receiver mode. These options help separate different use cases. Android mode provides access to apps and broader smart-device functions, while pure music mode is intended to keep the interface focused on playback. USB DAC mode lets the player handle audio from a computer or another compatible USB source, and Bluetooth receiver mode allows a phone or other source to transmit audio to the JM21 for wired headphone listening.

Internal storage consists of 3 GB of RAM and 32 GB of ROM, with approximately 22 GB available to the user. That built-in capacity is relatively modest for a large lossless library, but microSD expansion up to 2 TB is the more important provision for a dedicated music player. It allows owners to carry a substantial collection without relying entirely on network access or occupying the internal system storage.

Balanced hardware and carefully divided circuitry

At the conversion stage, the JM21 uses two Cirrus Logic CS43198 DACs, partnered by two SGM8262 operational amplifiers. This dual-DAC, dual-amplifier arrangement supports a fully balanced signal path and the player’s 4.4 mm balanced headphone output. A conventional 3.5 mm single-ended output is also included, so existing headphones do not require balanced termination to be used with the player.

FiiO has divided the internal design into dedicated zones for the DAC, amplifier and control components. The intention is to reduce interaction and crosstalk between sensitive audio circuitry and the sections responsible for processing and user control. A segmented power architecture uses four independent regulators, including low-noise LDO regulation, to distribute power across the different functional areas.

The company’s Digital Audio Purification System adds a fifth-generation FPGA and two femtosecond oscillators. This subsystem is designed to manage the digital signal and provide stable timing before conversion. These are meaningful engineering choices in a compact product, where digital processing, wireless radios, power regulation and analog amplification must all share limited internal space.

Output options for different headphones

The balanced 4.4 mm connection delivers up to 700 mW per channel into 32 ohms at less than 1% THD+N, while the 3.5 mm single-ended output is specified at 245 mW per channel under the same load and distortion condition. The balanced connection therefore offers substantially more available output power for headphones that benefit from additional amplifier headroom. The single-ended socket remains the convenient choice for common portable headphones and earphones.

Three gain settings and three volume curves give owners more control over how the volume adjustment behaves with different loads. This is especially useful in a player expected to work with both sensitive in-ear monitors and less efficient over-ear designs. The published output impedance is below 1 ohm, with a specified noise level below 1.5 µV, figures that underline the JM21’s intended compatibility with sensitive earphones as well as more demanding headphones.

Its stated signal-to-noise ratio is at least 130 dB, while THD+N is specified below 0.0006%. These are manufacturer specifications rather than listening impressions, but they show that low noise and controlled distortion were explicit design priorities. Prospective owners should still match headphone requirements to the appropriate output, gain setting and available power rather than assuming every headphone presents the same demands.

More than a self-contained music player

The JM21’s connectivity allows it to move between portable and stationary roles. Its USB Type-C connection supports charging, data transfer and USB audio. In asynchronous USB DAC mode, it can operate as an external audio device at up to 384 kHz/32-bit PCM and native DSD256. This gives a laptop or desktop computer access to the player’s DAC and headphone amplifier without requiring a separate desktop unit.

The USB Audio digital output is specified for PCM up to 768 kHz/32 bit and DSD512, with DoP, D2P and native support. The 3.5 mm connection can also provide SPDIF output, including PCM up to 384 kHz/24 bit and DSD128 through supported DoP or D2P methods. These digital outputs allow the JM21 to act as a transport for an external DAC, making it relevant to a home system even when its internal conversion and amplification are not being used.

Local playback supports PCM up to 384 kHz/32 bit and native DSD256. The importance of this capability is less about pursuing large format numbers for their own sake and more about accepting a wide range of music files without requiring routine conversion before transfer.

Two-way Bluetooth and wireless flexibility

Bluetooth 5.0 operates in both directions. The JM21 can transmit music to wireless headphones, speakers or another compatible Bluetooth device, and it can receive a Bluetooth stream from an external source when used in receiver mode. LDAC is available for two-way transmission, and the listed codec support also includes SBC, AAC, aptX, aptX HD and LHDC.

This two-way implementation makes the player adaptable. An owner can use wired headphones when the internal DAC and amplifier are the priority, switch to wireless headphones for convenience, or send music from a phone to the JM21 and continue listening through its wired outputs. Codec availability will still depend on the capabilities of the device at the other end of the connection.

Battery life reflects the chosen output

The 2400 mAh battery is rated for up to 12.5 hours of operation when using the single-ended output and 9.5 hours when using the balanced output. The difference is a useful reminder that the higher-powered balanced amplifier places greater demand on the battery. Owners can choose between longer portable runtime and the additional output capability of the 4.4 mm connection according to the headphones being used.

Charging takes approximately two hours with a 5 V, 2 A supply. That combination of operating time and charging speed is practical for daily commuting, office listening or extended sessions away from a larger system, although users relying heavily on Wi-Fi, applications or high-output balanced playback should plan around the documented battery limits.

Conclusion

The FiiO JM21 is most suitable for listeners who want a compact dedicated player without giving up Android applications, expandable local storage or serious system connectivity. Its strongest documented qualities are the dual CS43198 DAC architecture, 700 mW-per-channel balanced output, selectable gain and volume behavior, two-way Bluetooth, Wi-Fi streaming and the ability to work as either a USB DAC or digital transport. Sensitive in-ear monitors, conventional portable headphones and more demanding over-ear models are all addressed through its two analog outputs and adjustable amplifier settings. It also makes sense for owners who want one portable source that can connect to an external DAC or active audio system at home. Those seeking a large smartphone-style screen or extensive built-in storage should note the compact 4.7-inch display and 22 GB of user-accessible internal capacity, although microSD support up to 2 TB directly addresses the latter. At $200, the JM21’s attraction lies in how many credible audio roles FiiO has fitted into a slim, 156 g device.