ЦАПы — FiiO S15

The S15 is a full-width desktop streamer from FiiO that joins network playback, digital conversion and a preamp stage inside an all-metal case 430 mm wide. It runs a horizontally oriented build of Android 12 on a Qualcomm Snapdragon 660 with 4 GB of RAM and 64 GB of storage, and a 7.84-inch automotive-grade colour LCD in the front panel works as a touchscreen. Conversion is handled by the AKM pairing of an AK4191EQ digital stage and an AK4499EX converter.

Key specs that matter

FiiO specifies a signal-to-noise figure of 131 dB or more (A-weighted), a noise floor below 1.8 µV and THD+N under 0.00023% at 1 kHz into 10 kohm. The response runs from 20 Hz to 70 kHz with less than 2.8 dB attenuation. In preamp mode the RCA outputs reach 4.5 Vrms and the balanced XLR outputs 8.9 Vrms, against fixed line levels of 2.4 Vrms and 4.8 Vrms. Files stored locally play up to 384 kHz/32-bit and DSD256, while the USB DAC input accepts 768 kHz/32-bit and native DSD512. The case measures 430 x 274.5 x 89.5 mm, and FiiO puts the weight at about 5.6 kg.

Engineering and use context

Splitting digital filtering (AK4191EQ) from the analogue conversion (AK4499EX) keeps the two tasks on separate chips, and AKM DWA Routing is used to lower noise. OPA1612 op-amps sit in the I/V and low-pass filter sections, and the analogue path stays fully balanced from the converter through the preamp. Two ACCUSILICON AS318-B femtosecond oscillators at 45.1584 MHz and 49.152 MHz clock the two sample-rate families, and FiiO's DAPS system is designed to play every file without resampling. Power comes from a 35 W linear supply with a custom transformer and four 4700 µF ELNA capacitors, followed by separate digital and analogue rails with precision LDO regulators. Physical partitions and shields divide the digital, analogue and power sections. An XMOS XU316 runs the USB interface, and a QCC5125 chip provides Bluetooth 5.1 with LDAC and aptX. Control is by two knobs, two virtual keys, a gesture-capable Bluetooth remote and a phone app.

Pairing

Digital inputs cover USB, HDMI, AES/EBU, optical and coaxial, with an SSD slot, an SD card slot and USB host ports for local libraries. Beyond RCA and XLR, the S15 sends signals out over HDMI ARC, I2S via HDMI, AES/EBU, optical and coaxial, so it can drive a TV setup or an external converter. The RCA and XLR outputs switch between fixed line level for an integrated amplifier and variable level for power amplifiers. Streaming support includes Roon Ready, AirPlay, DLNA, Spotify, Tidal, Qobuz, Amazon Music and Deezer, plus UPnP, SMB and WebDAV network shares over Wi-Fi or Ethernet.

Alternatives

The FiiO K17 uses the same AK4191 front end but splits conversion across two AK4499EX chips, one per channel, and adds a headphone amplifier.