M33 R2R Portable High-Resolution Audio Player

FiiO M33 R2R is a next-generation portable audio player designed to deliver high-end performance both on the go and in desktop setups. Powered by the Qualcomm Snapdragon 680 platform and running Android 13, it features 8 GB of RAM and 128 GB of internal storage, ensuring smooth operation, responsive multitasking, and seamless media streaming over time.

At its core is FiiO’s proprietary R2R DAC, an innovative technology brought for the first time from desktop systems into a portable device. This fully differential 24-bit resistor ladder DAC features a four-channel design with a total of 192 precision thin-film resistors (0.1% accuracy and low thermal drift), delivering the rich, natural warmth typical of R2R technology combined with highly accurate and balanced sound reproduction.

The audio section has been meticulously engineered with multi-stage circuits using Texas Instruments components. The preamplifier stage employs fully differential TI Burr-Brown OPA1637 operational amplifiers, while the output stage utilizes four INA1620 amplifier chips in a parallel configuration. This design enables a powerful output of up to 1100 mW + 1100 mW, capable of effortlessly driving both sensitive in-ear monitors and demanding over-ear headphones, while maintaining excellent dynamics, control, and detail.

The power supply system is equally advanced, featuring independent supplies for digital and analog sections, with further subdivision for the R2R DAC, preamplifier, and amplification stages. The architecture includes 65 high-current MOSFETs, large-capacity capacitors, and a 15 W power management system, ensuring stability, efficiency, and consistent performance. A dedicated over-ear headphone mode activates a higher voltage rail to further increase output power.

To ensure maximum signal purity, the device incorporates multi-stage internal shielding, with separate compartments for digital processing, R2R array, amplification, and power modules. This significantly reduces interference and crosstalk, resulting in an exceptionally quiet background and a more precise, well-defined soundstage.

The proprietary DAPS (Digital Audio Purification System), based on a high-performance FPGA and dual femtosecond-grade crystal oscillators, provides an ultra-precise clock with extremely low jitter. Derived from the flagship M27, this system significantly improves digital signal processing efficiency and fidelity.

The XMOS XU316 chip enables high-performance USB DAC functionality, offering ultra-low latency and perfect audio-video synchronization across different use cases.

The 5.5-inch Full HD display (1080 x 2160), fully laminated and protected by third-generation Corning Gorilla Glass with an oleophobic coating, delivers an immersive visual experience. The interface includes retro-style visualizations such as cassette animations, spectrum displays, and VU meters, enhancing the overall listening experience.

The design is sleek and minimalist, featuring an 18:9 aspect ratio, refined lines, and high-quality finishes. The matte AG glass back provides a smooth, comfortable feel, improving ergonomics and handling.

On the software side, the device offers great flexibility with five operating modes: Android, Pure Music, AirPlay, USB DAC, and Bluetooth. Customizable multifunction buttons allow quick access to frequently used features.

A 10-band parametric equalizer enables precise sound tuning, while the Auto EQ function automatically adjusts frequency response based on the connected headphones. Two sound profiles are also available: “Flat” and “Warm”.

Connectivity is extensive and versatile. The player includes 3.5 mm and 4.4 mm headphone outputs (single-ended and balanced), dedicated line outputs, a low-jitter coaxial SPDIF output (71.5 ps), USB audio output, and high-resolution bidirectional Bluetooth. Bluetooth transmission supports SBC, aptX, aptX HD, LDAC, and LHDC, while reception supports SBC and LDAC.

Dual USB Type-C ports further enhance usability. Thanks to the patented desktop mode, the device can be powered directly while bypassing the battery, reducing wear and ensuring optimal performance during extended use.

Battery life is supported by a 4400 mAh capacity, providing up to 15.5 hours of playback in single-ended mode and 13.5 hours in balanced mode. Fast charging at 30 W allows a full recharge in approximately 1.5 hours while maintaining low operating temperatures.

The device is also compatible with RETRO BOX, offering a unique and versatile listening experience both as a portable source and as a desktop audio solution.

Key Specifications

Processor: Qualcomm Snapdragon 680
Operating System: Android 13
RAM: 8 GB
Internal Storage: 128 GB (approx. 112 GB usable)
Expandable Storage: microSD up to 2 TB

DAC: FiiO proprietary R2R
USB Chip: XMOS XU316
Display: 5.5” Full HD (1080 x 2160)

Bluetooth
Reception: 5.0 (SBC, LDAC)
Transmission: 5.0 (SBC, aptX, aptX HD, LDAC, LHDC)

Decoding
Local playback: up to 384 kHz / 32-bit, DSD256 native
USB DAC: up to 768 kHz / 32-bit, DSD512 native
USB audio: up to 768 kHz / 32-bit, DSD512 (DoP/D2P/native)
Coaxial output: up to 384 kHz / 24-bit, DSD128

Headphone Output
Balanced: up to 1100 mW + 1100 mW (32 Ω, over-ear mode)
Single-ended: up to 470 mW + 470 mW (32 Ω)

Audio Parameters
Frequency response: 20 Hz – 40 kHz
SNR: ≥117 dB
THD+N: PCM 0.0183% / DSD 0.0033%
Crosstalk: ≥74 dB

Battery
Capacity: 4400 mAh
Playback time: up to 15.5 hours
Fast charging: 30 W

Dimensions: 138.2 x 71.5 x 17 mm
Weight: approx. 258 g
Colors: Retro Gold, Dark Blue, Black

Package Contents

- M33 R2R
- USB data cable
- Leather case (pre-installed)
- Screen protector (pre-installed)
- Warranty certificate
- Quick start guide