Portable R2R player FiiO M33 Black

Portable R2R player FiiO M33

FiiO M33 is a portable music player built on R2R architecture, which compared to common delta-sigma converters focuses on a more natural and musical sound presentation. It is based on precise voltage steps and natural timing, traits often associated with a more "analog" reproduction character. A fully differential 24-bit R2R resistor ladder uses 192 precise thin-film resistors with 0.1 % tolerance, delivering exceptionally clean and balanced sound with emphasis on dynamics, soundstage and naturalness. There is also the option to switch between OS and NOS modes, allowing selection of oversampling for higher accuracy or non-oversampling for a more direct signal path and a more authentic reproduction character. The M33 is therefore not just an ordinary on-the-go player, but a full-fledged audiophile source capable of replacing even a quality desktop DAC and headphone amplifier.

From desktop R2R DAC to portable player

FiiO has integrated its own R2R architecture, originally developed for desktop audio equipment, into a compact portable player for the first time. The result is a combination of the typical analog character of R2R converters with a modern portable solution for everyday listening at home and on the go. The M33 also offers a special desktop mode with a pair of USB-C ports that separate power from playback to minimize interference and ensure more stable sound during long-term use. Thanks to this it can function not only as a portable player but also as a full-featured desktop DAC and preamplifier for home audio systems. The built-in 4400 mAh battery provides up to 15.5 hours of playback and supports fast 30W charging with emphasis on low heating during charging.

Android 13, Snapdragon 680 and flagship headphone amplifier

At the heart of the FiiO M33 is an octa-core Qualcomm Snapdragon 680 processor supplemented by 8 GB RAM and the Android 13 operating system, ensuring smooth system operation and streaming apps. The large 5.5" Full HD display with 1080 × 2160 px resolution provides clear control, a modern UI and visualizations inspired by classic Hi-Fi components. Power is handled by a fully differential headphone amplifier using top TI Burr-Brown components including OPA1637 operational amplifiers and a quartet of INA1620 amplifier chips. Balanced output power up to 1100 mW + 1100 mW at 32 Ω allows driving sensitive IEMs as well as demanding high-impedance over-ear headphones. The analog section uses separate power supplies for digital and analog sections, multi-level shielding and Rubycon film capacitors for maximally clean signal, low noise and stable sound even under high load.

Hi-Res audio and modern connectivity

The FiiO M33 supports high-resolution playback up to 384 kHz / 32 bit and DSD256 in local playback, while in USB DAC mode it handles up to 768 kHz / 32 bit and DSD512 thanks to the dedicated XMOS XU316 USB chip with ultra-low latency. This chip not only ensures stable signal transfer but also precise audio synchronization when used with a computer or laptop. Bidirectional Bluetooth with support for LDAC, LHDC, aptX HD or aptX Adaptive is standard, allowing wireless streaming at significantly higher quality compared to ordinary Bluetooth. Balanced and unbalanced headphone and line outputs, USB audio and coaxial SPDIF digital output are available, so the M33 can function as a portable player, desktop DAC, preamplifier or digital transport for external audio systems.

Main features

• Portable Hi-Res music player with FiiO's own R2R architecture.
• Fully differential 24-bit R2R resistor ladder with 192 precise thin-film resistors.
• OS / NOS modes to choose between oversampling and a more direct signal path.
• Qualcomm Snapdragon 680 processor and Android 13 operating system.
• 8 GB RAM and 128 GB internal storage.
• Support for microSD / TF cards up to 2 TB capacity.
• 5.5" Full HD display with 1080 × 2160 px resolution.
• Dedicated XMOS XU316 USB chip with ultra-low latency.
• USB DAC up to 768 kHz / 32 bit and DSD512.
• Local playback up to 384 kHz / 32 bit and DSD256.
• Balanced power up to 1100 mW + 1100 mW at 32 Ω.
• Four gain levels including a mode for demanding over-ear headphones.
• TI Burr-Brown OPA1637 operational amplifiers and INA1620 amplifier chips.
• Rubycon film capacitors and separate power for digital and analog sections.
• Multi-level shielding to minimize noise and crosstalk.
• Balanced 4.4 mm and unbalanced 3.5 mm headphone outputs.
• Balanced and unbalanced line outputs for connecting an external amplifier or active speakers.
• USB audio and coaxial SPDIF digital output.
• Bidirectional Bluetooth 5.0 with support for LDAC, LHDC, aptX HD and aptX Adaptive.
• Support for streaming apps and local music library.
• Desktop mode with separate power and playback via dual USB-C ports.
• Can be used as a portable player, desktop DAC, preamplifier or digital transport.
• Built-in 4400 mAh battery with up to 15.5 hours of playback.
• Fast 30W charging with temperature-optimized charging.
• Elegant construction with AG glass and minimalist design.

Evaluation

• FiiO