FiiO K17 R2R DAC and Headphone Amplifier

R2R Architecture
Built on a segmented architecture, the upper 5 bits are decoded through 31 thermometer-coded resistors, minimizing the error accumulation often found in traditional R2R designs and reducing distortion. The result is a sound that captures everything listeners love about R2R, clear yet smooth, natural, warm, and effortlessly listenable.

Play Anything from Anywhere
With Roon Ready, AirPlay, and Qplay certifications, the K17 R2R works seamlessly with the platforms and devices you already use. Newly added NAS server playback brings your home music library into the picture, supporting NFS and SMB protocols with one-tap access via the FIIO Control app. From cloud streaming to lossless local network playback, whatever you want to hear, the K17 R2R gets it to your ears.

8 Operating Modes
The K17 R2R delivers versatile connectivity with support for Roon Ready, QPlay, and AirPlay streaming, along with local playback via onboard storage or a LAN NAS. It accepts both single-ended and balanced analog inputs for amplification, while USB decoding is powered by the XMOS XU316 for up to 768kHz/32-bit, DSD256, and full MQA support. Bluetooth 5.1 is handled by the Qualcomm QCC5125, with aptX HD, aptX Adaptive, and LDAC compatibility, and additional digital inputs include optical and coaxial connections.

Discrete Class AB Headphone Amplifier
An vital part of the K17 R2R is its carefully crafted fully discrete amplifier circuit. This discrete circuit is of an OP+ transistor current amplification design, equipped with the classic pair of ON Semiconductor MJE243/253 transistors. It is capable of producing high current with low output impedance.

The result is up to 4000mW+4000mW output power in balanced mode, nearly double that of the K9 Pro ESS. This allows it to easily drive various kinds of headphones and IEMs and to produce smooth, pleasant, and natural sound.

Fully Balanced Design
From the DAC, to the I/V conversion, to the low-pass filtering, and to headphone amp, the entire audio circuit is of a fully differential circuit architecture design. This ensures both high dynamic range of the signals as well as significantly reduced crosstalk. Various parts of the audio circuit, including the I/V conversion and LPF stages, use multiple low-noise precision Texas Instruments (TI) op-amps to ensure dynamic audio output.