The KA17 is FIIO's flagship model and is the first USB dongle to feature the THX headphone amp circuit. It utilizes the latest THX AAA 78+ headphone amplifier architecture, which consists of 4 fully balanced channels and 8 parallel-connected op-amps. This configuration significantly increases the output power, especially in Desktop Mode where the balanced output power can reach up to 650mW + 650mW. This gives the KA17 the dynamics, control, and sound reproduction quality similar to that of a desktop amplifier.

For the DAC, the KA17 integrates two newly released ESS dual-channel flagship DACs, ES9069Q. These DACs are based on the fourth-generation 32-bit HyperStream architecture, offering higher performance and lower power consumption. They also effectively reduce digital noise inside the DAC, resulting in a remarkable dynamic range of 130dB and a THD+N rating of -120dB. This ensures outstanding performance and a purer sound background.

The KA17 also incorporates the professional-grade XMOS 16-core chip, XU316, which is rarely found in USB dongles. This chip provides lower latency, more stable transmission, and better compatibility. It supports high-resolution audio up to 768kHz/32bit, native DSD512 decoding, and MQA full decoding. Dual audio crystal oscillators further enhance its ability to adapt to various sources and sampling rates accurately.

The KA17 features a 0.91-inch dot matrix display that intuitively indicates different functions. It is complemented by physical buttons that make it easy to customize settings such as screen orientation, filters, and display sleep timer.

Furthermore, the KA17 stands out by offering PEQ adjustment, a feature not commonly found in USB dongles. It supports ten customizable frequency bands, allowing users to fine-tune EQ bands, gain level, and bandwidth using FIIO's independently developed adjustment algorithm and interface. This greatly enhances the device's playability.

Despite its compact size, the KA17 houses a multi-stage HiFi audio architecture similar to that of a dedicated audio player. It includes separate digital and analog boards to prevent crosstalk, a 3-stage 10-rail power supply design, and comes with a matching leatherette case. It also incorporates built-in temperature detection and output DC detection, supports 60 and 120 levels of volume adjustment, and even offers SPDIF output capability.