Overview

The FiiO S15 is a flagship desktop all-in-one media streamer, DAC, and preamp designed for high-end home audio systems. This comprehensive device features AKM’s flagship AK4191+AK4499EX DAC combination, Android 12 operating system with a 7.8-inch touchscreen, and extensive connectivity including HDMI ARC, I2S, AES, and balanced XLR outputs. The S15 supports high-resolution audio up to PCM 768kHz/32-bit and native DSD512 via USB, with comprehensive streaming capabilities including Roon Ready certification. Built with a robust 5kg all-metal chassis and 35W linear power supply, it represents FiiO’s flagship approach to desktop streaming solutions.

Scientific Validity

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Manufacturer specifications for the S15 report signal-to-noise ratio of ≥131dB, THD+N <0.00023%, frequency response from 20Hz to 70kHz, and noise floor <1.8μV (A-weighted) [1]. While these specifications exceed transparent levels, independent third-party measurement results are not available for verification. When relying solely on manufacturer specifications, conservative evaluation is necessary, and actual measured performance awaits independent verification.

Technology Level

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The S15 incorporates flagship-level technology with AKM’s AK4191+AK4499EX DAC combination featuring DWA ROUTING Technology for enhanced signal-to-noise ratio [1]. The implementation includes dual ACCUSILICON AS318-B ultra-low phase noise femtosecond oscillators, XMOS XU316 16-core USB processor, and Qualcomm Snapdragon 660 powering a customized Android 12 interface. The fully balanced design extends from DAC decoding through the preamplifier stage, utilizing OPA1612 precision op-amps and a shielded 35W linear power supply with four 4700μF ELNA capacitors. While representing solid technical implementation with current flagship components and advanced software integration, it primarily utilizes established technologies rather than pioneering entirely new approaches.

Cost-Performance

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The S15 offers comprehensive functionality including flagship DAC implementation, Android streaming platform, touchscreen interface, and extensive I/O connectivity. While the S15 achieves superior measured performance (SNR ≥131dB vs 121dB, THD+N <0.00023% vs <0.00018%), the WiiM Ultra provides functionally equivalent streaming capabilities with Roon Ready certification, HDMI ARC support, high-resolution audio support up to PCM 384kHz, preamp functionality, and touchscreen interface at significantly lower cost [2]. Equipped with ES9038Q2M SABRE DAC, comprehensive connectivity including RCA, optical, coaxial, USB, phono input, and headphone output, the WiiM Ultra delivers equivalent user-facing functionality for core streaming and DAC applications, despite the S15’s technical measurement advantages.

CP = 329 USD ÷ 999 USD = 0.33

Reliability & Support

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The S15 benefits from robust physical construction with its 5kg all-metal chassis, linear power supply design, and quality component selection suggesting inherent durability. However, user reports indicate software reliability concerns, with one user noting “the software is not good” despite satisfaction with hardware quality [3]. FiiO’s support structure relies primarily on regional dealer networks, with some documented customer service difficulties in past cases. The combination of solid hardware construction but software stability concerns and variable support experience results in below-average reliability expectations.

Rationality of Design Philosophy

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FiiO demonstrates a measurement-focused approach with flagship DAC implementation and comprehensive feature integration that directly contributes to functional capabilities. The adoption of current flagship technologies, Android-based software platform, and extensive connectivity options reflects rational engineering decisions for a premium streaming solution. The integration of touchscreen interface, comprehensive I/O options, and high-resolution audio support provides clear user benefits. However, the approach represents incremental advancement rather than breakthrough innovation, following established premium streamer concepts rather than pioneering new directions in digital audio delivery.

Advice

The FiiO S15 delivers exceptional measured performance and comprehensive functionality for users requiring a flagship desktop streaming solution with extensive connectivity and Android-based operation. The device excels in technical performance metrics and provides a complete streaming ecosystem with touchscreen control. However, potential buyers should carefully consider the significant price premium relative to alternatives offering similar core functionality. Those prioritizing measured performance and comprehensive features may find value, while cost-conscious users should evaluate whether the premium justifies the additional capabilities over more affordable streaming solutions.

References

[1] FiiO, Professional and Versatile, FIIO’s Desktop High-Res Audio Streamer S15 Is Officially Released!, https://www.fiio.com/newsinfo/986774.html, 2025, Audio parameters: SNR ≥131dB (A-weighted), THD+N <0.00023% (1kHz/0dB@10kΩ)

[2] WiiM, WiiM Ultra Specifications, https://www.wiimhome.com/wiimultra/specs, 2025, ES9038Q2M SABRE DAC, SNR 121dB/THD+N <0.00018% (line out), PCM 384kHz/24-bit Hi-Res support, HDMI ARC, Roon Ready certified

[3] Steve Hoffman Music Forums, Any of you have experience with FiiO warranty service?, https://forums.stevehoffman.tv/threads/any-of-you-have-experience-with-fiio-warranty-service.447664/, Accessed 2025-09-13, User reports software reliability concerns

(2025.9.13)