FiiO M33 R2R – high-res DAP with 24-bit R2R DAC and Android 13

The FiiO M33 R2R is a high-performance Digital Audio Player designed for listeners who want the flexibility of a modern Android device combined with a fully differential 24-bit R2R DAC architecture. It brings together high-resolution playback, streaming, powerful headphone outputs, advanced EQ and a dedicated Desktop Mode in one versatile portable player.

Within the FiiO range, the M33 R2R is particularly attractive to listeners looking for more memory, amplifier power and an alternative DAC architecture. Explore our full selection of Digital Audio Players and high-end DAPs.

Fully differential 24-bit R2R DAC

The defining feature of the M33 R2R is FiiO’s proprietary R2R converter. Its four-channel architecture uses a total of 192 precision thin-film resistors. Rather than relying on a conventional delta-sigma DAC chip, digital-to-analogue conversion is performed through a carefully matched resistor-ladder network.

R2R conversion is valued by many hi-fi enthusiasts for its coherent and natural presentation. FiiO combines the converter with a multi-stage analogue audio circuit using Texas Instruments components and its proprietary DAPS digital audio processing architecture.

NOS and OS playback modes

The M33 R2R offers both NOS (Non-Oversampling) and OS (Oversampling) PCM modes. NOS retains the original PCM sampling rate, while OS upsamples the signal to 352.8 or 384kHz. This gives the listener an additional way to tailor playback to personal preference.

Powerful 3.5mm and 4.4mm outputs

The player provides both a 3.5mm single-ended output and a 4.4mm balanced output. When connected to a suitable fast charger, Super High Gain / Over-Ear Headphone Mode can be activated. The 4.4mm output can then deliver up to 1100mW + 1100mW into 32 ohms, while the 3.5mm connection can provide up to 470mW + 470mW into 32 ohms.

FiiO specifies a recommended headphone impedance range of approximately 8 to 350 ohms.

Android 13, Snapdragon 680 and 8GB RAM

A Qualcomm Snapdragon 680 processor and 8GB of RAM provide smooth navigation, app use and multitasking. Android 13 allows popular streaming services such as TIDAL, Qobuz and Spotify to be used directly on the player.

The M33 R2R includes 128GB of internal storage, with approximately 112GB available to the user, plus microSD expansion up to 2TB.

XMOS XU316 and high-resolution USB DAC

Local playback supports up to 384kHz/32-bit PCM and Native DSD256. When used as a USB DAC, the XMOS XU316 interface supports up to 768kHz/32-bit PCM and Native DSD512. USB Audio and coaxial digital output are also supported.

Five independent operating modes

• Android Mode – apps, streaming and local playback.
• Pure Music Mode – focused local music playback.
• AirPlay Mode – wireless playback from compatible Apple devices.
• USB DAC Mode – use the M33 R2R as an external DAC.
• Bluetooth Receiver Mode – use the player as a Bluetooth audio receiver.

Desktop Mode with battery bypass

FiiO’s Desktop Mode allows the M33 R2R to draw power directly from a suitable external USB power supply. Under normal operating conditions this bypasses the internal battery, helping to reduce unnecessary charge and discharge cycles during prolonged desktop use.

10-band PEQ and AUTO EQ

A 10-band parametric equalizer provides extensive control over frequency response. AUTO EQ is also supported, together with selectable sound profiles, making it easier to adapt the player to different headphones and listening preferences.

Bluetooth and Wi-Fi connectivity

Bluetooth 5.0 transmission supports SBC, aptX, aptX HD, LDAC and LHDC, while Bluetooth reception supports SBC and LDAC. Dual-band 2.4/5GHz Wi-Fi provides support for DLNA, AirPlay and Wi-Fi Music Transfer.

FiiO M21, M33 R2R or M27?

The FiiO M21 is worth considering when compact size and a lower entry price are priorities. The M33 R2R is aimed more specifically at users who want R2R conversion, 8GB RAM, greater internal storage and more powerful balanced amplification.

For those looking for FiiO’s flagship portable player, the FiiO M27 sits above the M33. The M33 R2R therefore occupies a particularly interesting position for listeners seeking serious high-end performance without immediately moving to the flagship level.

FiiO M33 R2R technical specifications

*Battery figures are based on FiiO laboratory test conditions. Actual performance depends on use and settings.

Frequently asked questions

Does the FiiO M33 R2R support streaming apps?
Yes. Android 13 allows popular music streaming apps to run directly on the player.

Can the M33 R2R be used as a USB DAC?
Yes. USB DAC playback supports up to 768kHz/32-bit PCM and Native DSD512.

What are NOS and OS modes?
NOS retains the original PCM sample rate, while OS applies oversampling to 352.8 or 384kHz.

Does the M33 R2R have a balanced output?
Yes. A 4.4mm balanced headphone/line output is provided alongside the 3.5mm connection.

Can it be used in a desktop system?
Yes. Desktop Mode allows external USB power and battery bypass during normal desktop operation.

How much storage does it offer?
128GB internally plus microSD expansion up to 2TB.

Conclusion

The FiiO M33 R2R is an unusually versatile DAP for listeners who want R2R conversion without sacrificing Android streaming, high-resolution digital connectivity or substantial headphone power. Its combination of R2R DAC, OS/NOS modes, 10-band PEQ, balanced output and Desktop Mode makes it equally relevant for portable and desktop listening.