Two DAC Architectures for Portable Listening

The FiiO M25 and M25 R2R are portable high-resolution music players that offer two distinct DAC architectures alongside shared processing, playback, and connectivity features. The M25 combines an AKM AK4191EQ with two AK4499EX DACs, while the M25 R2R uses FiiO’s proprietary 24+5-bit segmented resistor array. Both include a Qualcomm QCS6490 processor, 8GB of RAM, and balanced output rated at up to 1700mW per channel into 32Ω with external power, supporting portable listening, desktop use, and USB DAC operation.

Two approaches to digital-to-analog conversion

The M25 and M25 R2R are separate hardware versions. The M25 uses AKM’s AK4191EQ and dual AK4499EX configuration. The M25 R2R performs conversion through a network of 316 high-precision, low-temperature-drift thin-film resistors. Its segmented architecture uses 31 thermometer-coded resistors for the upper five bits, helping reduce accumulated conversion errors and distortion.

FiiO describes the R2R version’s presentation as naturally warm. Its Natural FLAT and Mellow WARM profiles offer additional tonal choices, and either profile can be combined with Dynamic Range Enhancement. The M25 R2R also maintains four independent analog signal paths through decoding, volume control, and headphone amplification, with dedicated analog stages and BUF634A output buffers.

Output power that scales with external power

Four gain settings accommodate headphones with different power requirements. High gain provides 1000mW per channel into 32Ω through the balanced output. Connecting a compatible fast charger to either USB-C port enables Super High Gain Mode, increasing that figure to 1700mW per channel into the same load. Medium and low gain provide lower output levels for headphones that require less power.

The 4.4mm balanced and 3.5mm single-ended connections support headphone and line output, allowing either player to feed external amplification. FiiO’s patented Desktop Mode isolates the battery during externally powered operation, reducing unnecessary charging and discharging during extended desk use. Separate USB-C data/charging and charging/power inputs accommodate a source connection and external power supply.

Processing and storage for streaming and local playback

The eight-core Qualcomm Dragonwing QCS6490 processor runs at up to 2.7GHz and works with 8GB of RAM to support streaming apps, library browsing, and multitasking. Internal storage totals 128GB, with approximately 112GB available, while a microSD slot supports expansion up to a theoretical 2TB.

Android, Pure Music, AirPlay, USB DAC, and Bluetooth Receiving modes provide five ways to use the player. Bluetooth 5.2 reception supports SBC and LDAC. Transmission also supports aptX, aptX HD, aptX Adaptive, and LHDC, with codec availability determined by the connected device.

Dedicated hardware for digital audio

FiiO’s sixth-generation Digital Audio Purification System combines a high-capacity FPGA with custom dual femtosecond crystal oscillators to manage digital audio transmission and timing. Global SRC bypass, All to DSD, and Dynamic Range Enhancement provide additional playback options.

An independent XMOS XU316 USB interface supports use as an external DAC and headphone amplifier for compatible computers, phones, and tablets. Local playback and USB DAC operation support PCM up to 32-bit/768kHz and native DSD512. A coaxial output provides a digital connection to an external DAC.

31-band parametric EQ

Global 31-band parametric EQ lets you adjust frequency response for your headphones and listening preferences. AUTO EQ and preset sound profiles provide starting points for those adjustments. EQ sharing also lets you download community profiles or share your own curves.

Different battery runtimes, shared fast charging

Both versions use a 6500mAh battery and support 30W charge-pump fast charging, with QC3.0, QC4.0, PD2.0, PD3.0, and PPS compatibility. FiiO rates the M25 for approximately 9.5 hours of single-ended playback or 8.5 hours balanced. The M25 R2R is rated for approximately 14.5 hours single-ended or 12.5 hours balanced. Actual runtime varies with listening conditions and use.

A touchscreen with physical playback controls

A fully laminated 5.5-inch display provides a 1080 × 2160 resolution and an 18:9 aspect ratio. Physical volume and playback buttons keep common controls accessible, and a HOLD switch helps prevent accidental input. The angular, CNC-machined chassis is approximately 27g lighter, 0.9mm slimmer, and 4mm narrower than the M15S.

Availability

The FiiO M25 and M25 R2R are listed at Apos.