ЦАПы — FiiO K17

The FiiO K17 is a desktop unit from FiiO combining a network streamer, DAC, preamplifier and headphone amplifier in a 244.6 x 213 x 66.8 mm case that weighs about 2.75 kg. It sells for USD 989.99 in black or silver and ships with an IR remote, two USB cables and a spare fuse.

Key specs that matter

Digital conversion pairs an AKM AK4191 modulator with two AK4499EX chips, and the eight output channels are summed to four in the low-pass filter stage to cut common-mode interference. USB accepts PCM to 768 kHz at 32 bit and native DSD512 with full MQA decoding, coaxial takes 192 kHz at 24 bit and DSD64, and optical 96 kHz at 24 bit. Balanced headphone outputs on 4.4 mm and XLR4 produce at least 4000 mW per channel into 32 ohm and 950 mW into 300 ohm, with THD+N under 0.00049 percent and crosstalk of 119 dB. The 6.35 mm output provides 1850 mW into 32 ohm and 240 mW into 300 ohm. The XLR3 line output delivers 5 Vrms at SNR of 125 dB, and the RCA pair gives 2.5 Vrms. Frequency response is within 0.05 dB from 20 Hz to 20 kHz and within 3 dB up to 90 kHz.

Engineering and use context

A 35 W linear supply built around a custom transformer and five 4700 uF capacitors feeds separate digital and analog rails, with protection against transformer and amplifier overheating, output overload and DC. The headphone amplifier is fully discrete Class AB using ON Semiconductor MJE243 and MJE253 transistors, and the signal path is balanced throughout. An M21586Q DSP at 360 MHz computes a 31-band PEQ in 64-bit floating point, with gain from +12 to -24 dB and Q from 0.4 to 128, and an ES9821Q converter digitises the RCA and balanced analog inputs so they can pass through that EQ. Three femtosecond oscillators, OPA1612 op-amps, Panasonic film capacitors and gold-plated Neutrik sockets are also used. Streaming is Roon Ready with AirPlay and QPlay certification, over Gigabit Ethernet or a dual-band AP6256 Wi-Fi module, and NAS shares mount through NFS or SMB. Bluetooth 5.1 via a QCC5125 chip covers LDAC and aptX Adaptive.

Pairing

Headphones from 8 to 150 ohm suit the single-ended jack and from 8 to 350 ohm the balanced sockets, with a choice of five gain settings. Output impedance is below 1 ohm single-ended and 1.5 ohm balanced. A trigger input can switch the unit with an amplifier, and coaxial and optical outputs pass digital audio to an external converter.

Alternatives

The FiiO K17 R2R Pro keeps this platform but replaces the AKM chips with a 24+5-bit R2R resistor array offering NOS and OS modes.