FiiO M33 R2R – portable Android player with true R2R conversion

The FiiO M33 R2R is a high-resolution Digital Audio Player for listeners who want the flexibility of Android streaming combined with a fully differential 24-bit R2R DAC. With 8GB of RAM, 128GB of internal storage, powerful headphone outputs and a dedicated Desktop Mode, the M33 R2R is suitable for both portable listening and use in a home audio system.

It is positioned between the compact FiiO M21 and the flagship M27. This makes the M33 R2R especially interesting for listeners who specifically want R2R conversion, substantial amplifier power and extensive connectivity without immediately moving to FiiO’s top model.

Fully differential 24-bit R2R DAC

At the heart of the M33 R2R is FiiO’s proprietary fully differential R2R converter. Its four-channel architecture uses 192 precision thin-film resistors to perform digital-to-analogue conversion through carefully matched resistor networks rather than a conventional delta-sigma DAC chip.

R2R designs are appreciated by many hi-fi listeners for their coherent and natural presentation, although the final sound also depends on the headphones, recordings and selected settings. FiiO combines the R2R converter with a multi-stage analogue circuit using Texas Instruments op-amps and the DAPS Digital Audio Purification System derived from the M27.

NOS and OS playback modes

The FiiO M33 R2R offers both NOS and OS playback modes for PCM audio. In NOS mode, the original sampling rate of the signal is retained. In OS mode, the signal is oversampled to 352.8 or 384kHz before conversion. This allows the listener to select the processing method that best suits the system and personal preference.

Powerful outputs for IEMs and headphones

The player is equipped with a 3.5mm single-ended connection and a 4.4mm balanced connection. Both can function as a headphone output or line output, while the 3.5mm connection can also provide a coaxial digital output.

When the M33 R2R is connected to a suitable fast charger, Super High Gain or Over-Ear Headphone Mode can be activated. The balanced 4.4mm output can then deliver up to 1100mW + 1100mW into 32 ohms. The 3.5mm output can deliver up to 470mW + 470mW into 32 ohms. FiiO recommends the player for headphones with an impedance of approximately 8 to 350 ohms.

Android 13 with streaming applications

A Qualcomm Snapdragon 680 processor, 8GB of RAM and Android 13 provide a responsive platform for local playback and music streaming. Applications such as Spotify, TIDAL and Qobuz can be installed directly on the player, allowing the M33 R2R to operate independently from a smartphone.

The player includes 128GB of internal storage, of which approximately 112GB is available to the user. A microSD card of up to 2TB can be added for larger music libraries.

Five operating modes

The M33 R2R can be adapted to several listening situations:

• Android Mode: for streaming apps, local music and general Android use.
• Pure Music Mode: for focused local music playback.
• AirPlay Mode: for wireless playback from compatible Apple devices.
• USB DAC Mode: for use as an external DAC with a computer or compatible source.
• Bluetooth Receiver Mode: for receiving audio wirelessly from another device.

Portable player and desktop DAC

FiiO’s dedicated Desktop Mode allows the M33 R2R to draw power directly from a suitable external USB power supply. During normal desktop operation, the internal battery is bypassed. This helps reduce unnecessary charging cycles when the player is used for extended periods as part of a desktop or home audio system.

The XMOS XU316 USB interface supports up to 768kHz/32-bit PCM and Native DSD512 in USB DAC mode. Local playback supports up to 384kHz/32-bit PCM and Native DSD256.

Equalizer, Wi-Fi and Bluetooth

A 10-band parametric equalizer provides detailed control over the frequency response. The player also supports AUTO EQ, making it easier to adjust playback for different headphones and personal listening preferences.

Dual-band 2.4 and 5GHz Wi-Fi supports functions including DLNA, AirPlay and Wi-Fi Music Transfer. Bluetooth 5.0 transmission supports SBC, aptX, aptX HD, LDAC and LHDC. In Bluetooth Receiver Mode, the M33 R2R supports SBC and LDAC.

FiiO M21, M33 R2R or M27?

View the FiiO M21, compare it with the FiiO M27 or explore all Digital Audio Players available from Hi-Stands.

Technical specifications FiiO M33 R2R

Battery life and maximum output figures are based on FiiO laboratory conditions. Actual performance depends on the selected settings, headphones, volume level and usage.

Frequently asked questions

Does the FiiO M33 R2R support streaming applications?
Yes. Android 13 allows compatible streaming applications such as Spotify, TIDAL and Qobuz to run directly on the player.

Can the M33 R2R be used as a USB DAC?
Yes. In USB DAC Mode, it supports PCM playback up to 768kHz/32-bit and Native DSD512 through the XMOS XU316 interface.

Can the internal battery be bypassed during desktop use?
Yes. Desktop Mode allows the player to draw power from a suitable external USB power supply while bypassing the internal battery during normal operation.

What is the difference between NOS and OS mode?
NOS retains the original PCM sampling rate. OS mode oversamples the PCM signal to 352.8 or 384kHz before digital-to-analogue conversion.

Is the M33 R2R suitable for demanding headphones?
The balanced output can deliver up to 1100mW per channel into 32 ohms in Super High Gain. Compatibility still depends on the impedance and sensitivity of the specific headphones.

Versatile R2R player for portable and desktop listening

The FiiO M33 R2R combines a fully differential R2R DAC with Android streaming, substantial balanced output power and flexible desktop operation. It is an attractive choice for listeners who want the character and processing options of an R2R design without giving up modern streaming apps, high-resolution USB playback or portable use.

Discover more products from FiiO or contact Hi-Stands if you would like advice about matching the M33 R2R with your headphones or audio system.