FiiO M25 Portable R2R PRO DAC High Resolution Music Player

The FiiO M25 R2R is a palm-sized player with a desktop-grade sound system built around FiiO’s own R2R PRO DAC, a 24+5-bit segmented resistor ladder in a fully differential, four-channel design. Up to 1,700mW per channel balanced drives demanding headphones, the battery lasts up to 14.5 hours, and a Qualcomm QCS6490 runs Android with 8GB of RAM, 128GB of storage, Wi-Fi and LDAC Bluetooth.

FiiO’s R2R PRO DAC

Instead of a DAC chip, the R2R PRO converts with a precise network of resistors. FiiO decodes the top five bits with 31 resistors in thermometer coding, which avoids the error build-up of a conventional ladder and lowers distortion, so you keep the natural, analogue character of R2R with more detail, dynamics and soundstage. Four independent channels run from the DAC through the volume control to the amplifier. Choose Natural or Warm sound, and a 31-band parametric EQ with AutoEQ works across the system.

Desktop power in your hand

Four gain levels run from sensitive in-ear monitors to Over-Ear Mode: connect a fast charger to either USB-C port and the balanced output rises to 1,700mW per channel into 32Ω (7.4Vrms). FiiO’s patented Desktop Mode runs the player from external power and bypasses the battery, so it can play at full power for long sessions without wearing the battery. The sixth-generation DAPS system, the same large FPGA as the M27 with two custom femtosecond clocks, keeps jitter very low, and a zoned, multi-stage power supply with KEMET and AVX tantalum capacitors, ruby film capacitors and low-noise film resistors keeps the background black.

Compact, with a retro side

The 5.5-inch 1080 × 2160 screen sits in a faceted, “diamond-cut” CNC aluminium body that fits in one hand. FiiO says that against the M15S it has 41% more power and is 27g lighter, 0.9mm thinner and 4mm narrower. A Qualcomm QCS6490 with 8GB of RAM keeps Android and streaming apps quick, and a retro interface adds Pod and cassette modes. The M25 R2R is also a USB DAC for a computer, phone or tablet (XMOS XU316, 768kHz/32-bit and native DSD512), an AirPlay receiver and a Bluetooth receiver.

Good to know

• Over-Ear Mode needs a fast charger (QC 3.0/4.0 or PD) connected to either USB-C port.
• The 3.5mm socket is shared by the headphone, line and coaxial outputs; the 4.4mm socket by the balanced headphone and line outputs.
• Two USB-C ports: USB 3.0 for data and charging, and POWER IN for charging or Desktop Mode.
• In the box: M25 R2R with leather case and screen protector fitted, USB cable, warranty card and quick start guide.
• Prefer a modern, highly detailed sound? See the AKM M25 VERITA. For FiiO’s flagship player, see the M27, and for the retro look, the FiiO RETROBOX speaker.