With the new FiiO M25, the Chinese manufacturer is updating its range of high-end DAPs and replacing the highly acclaimed FiiO M15S. More powerful, featuring a modernised Android platform and a completely redesigned audio architecture, this new model stands out above all for being available in two versions: one equipped with two AKM AK4499EX DACs, the other utilising a proprietary next-generation R2R converter. This caters to different listening preferences while maintaining the versatility of a portable DAP capable of replacing a full desktop DAC and headphone amplifier setup.
Two versions for two approaches to conversion
As the successor to the famous FiiO M15S, which was powered by an ESS Sabre ES9038PRO DAC, the new FiiO M25 marks a significant shift in the manufacturer’s strategy. Rather than providing a single configuration, FiiO now offers its DAP in two versions based on different digital-to-analogue conversion technologies.
The first, called the FiiO M25 VERITA, uses a dual AKM AK4499EX DAC architecture, while the FiiO M25 R2R features an in-house-developed resistor network. Both models share a modern processing platform, fully balanced amplification, and 1,700 mW of power per channel. The main difference lies in how they reconstruct the analogue signal and in the sound signatures the manufacturer aims to achieve.
Dual AKM AK4499EX DACs for the FiiO M25 VERITA
The FiiO M25 VERITA DAP features a particularly ambitious configuration based on two AKM AK4499EX DACs paired with an AK4191EQ digital signal processing chip. Each DAC is dedicated exclusively to converting a single channel, which helps preserve stereo separation and minimise interference between the left and right channels.
This architecture incorporates Velvet Sound technology from Japanese manufacturer AKM, with separate digital and analogue processing stages. The AK4191EQ modulator handles the digital processing upstream of the two AK4499EX converters, which are dedicated to reconstructing the analogue signal. This design better isolates the various stages of conversion and reduces interference that could affect the musical signal.
The manufacturer also highlights AKM’s DWA Routing technology, designed to improve conversion accuracy and circuit performance. FiiO also announces several sound profiles developed specifically for this version to tailor the sound to each listener’s preferences. This combination ensures optimal playback of Hi-Res audio up to 32-bit/768 kHz and DSD512.
FiiO M25 R2R PRO: a more analogue approach
At the same time, the FiiO M25 R2R PRO replaces delta-sigma converters with a proprietary, next-generation R2R architecture. Already explored by FiiO in several of its hi-fi devices, including the FiiO M33 R2R DAP, this technology relies on a network of high-precision resistors tasked with directly reconstructing the analogue signal from digital data.
For this DAP, FiiO has developed a 24 + 5-bit segmented R2R PRO circuit, incorporating nearly 400 precision resistors. The five most significant bits, in particular, use a thermometric encoding scheme with 31 resistors. This solution aims to reduce conversion errors and distortion that can occur in traditional R2R architectures, particularly due to component tolerances.
The goal is to preserve the qualities generally sought after in this technology—namely, a smooth, warm, and natural sound—while improving the resolution, dynamic range, and precision of the stereo image. The manufacturer therefore pays particular attention to the reproduction of timbres and vocals. Like the Delta Sigma version, the FiiO M25 R2R DAP supports files up to 32-bit/768 kHz and DSD512.
Up to 1,700 mW per channel
Beyond their DAC stages, the two FiiO M25 DAPs share the same architecture, notably featuring a fully balanced amplification section. The signal therefore maintains four independent paths from the DAC through the volume control and amplification stages all the way to the output stages. This design reduces crosstalk and better preserves the integrity of the left and right signals. FiiO also pays close attention to the power supply for the various circuits through multiple regulation stages and separate power supply zones in order to limit the spread of electrical interference.
As a result, the FiiO M25 DAP can deliver up to 1,700 mW per channel, compared to 1,200 mW for its predecessor, the FiiO M15S, when powered via USB in its most powerful mode. This extra power reserve should allow the new model to drive demanding headphones more comfortably while still maintaining enough finesse to pair with sensitive in-ear monitors. Like its predecessor, the FiiO M25 also features a Desktop mode that allows it to operate from an external power source without draining the battery. This is a particularly useful feature for using the DAP daily as a hi-fi source or as a DAC and headphone amplifier on a desk.
Digital processing inherited from the FiiO M27
To take full advantage of its new converters, the FiiO M25 features the sixth generation of the DAPS (Digital Audio Purification System) developed by the manufacturer. This architecture uses a high-capacity FPGA, similar to the one in the high-end FiiO M27 DAP, combined with two custom femtosecond quartz oscillators.
The system ensures exceptionally precise synchronisation of digital streams, with the goal of reducing jitter—that is, the minute temporal variations that can affect the transmission of audio data. FiiO seeks to preserve the stability of the signal before it is processed by the converters.
31-band parametric equaliser and Auto EQ
FiiO has also expanded the sound customisation options for its new DAP. The M25 features a 31-band parametric equaliser, offering exceptionally precise control over the frequency response. Consequently, more experienced users will be able to fine-tune the sound of their headphones or earbuds, correct certain frequency peaks, or customise the sound signature to suit their tastes.
To make these settings more accessible, FiiO has also added an Auto EQ feature designed to simplify automatic equalisation. Both versions also feature specific sound profiles developed by the manufacturer. The FiiO M25 VERITA offers several sound signatures associated with its AKM architecture, while the R2R PRO version places greater emphasis on a warm and natural sound.
Faster than ever
The manufacturer is also upgrading the M25’s entire computing platform with the adoption of a more powerful Qualcomm QCS6490 processor. This eight-core chip can reach a clock speed of 2.7 GHz, delivering a significant performance boost over the Snapdragon 660 found in the FiiO M15S. The processor is paired with 8 GB of RAM and 128 GB of internal storage. This configuration should ensure smooth navigation through the Android interface, even with a large music library or multiple apps running in the background.
The FiiO M25 also features a modernised design. Its metal chassis features angular lines and CNC-machined surfaces, with facets inspired by gemstone cutting. The front panel features a 5.5-inch high-definition touchscreen, large enough to make it easy to navigate through albums, playlists, and various settings. To power these components, the DAP is equipped with a 6,500 mAh battery that supports fast charging up to 30 W.
With the M25, FiiO offers a major evolution of its DAP, both in terms of performance and customisation options. The introduction of a dual architecture—AKM or R2R—is undoubtedly the most interesting new feature, as it allows users to choose a conversion technology based on their listening preferences without sacrificing the device’s amplification capabilities or versatility. Both versions will go on sale in the coming months for €1,249.
