FiiO K9 [Official Japanese Retailer] Desktop Headphone Amplifier with THX-AAA 788+

Equipped with dual ESS Technology high-performance ES9068AS DAC chips: The K9 features ESS Technology's top-of-the-line 2-channel output DAC chip, the ES9068AS, designed for audiophiles. The ES9068AS is configured in a dual configuration, with one chip per left and one per channel. Utilizing ESS Technology's Hyperstream II and QUAD DAC technologies, the ES9068AS delivers high-quality sound and compatibility with a wide range of file formats while consuming low power.

Fully balanced design from the DAC to the headphone amplifier: The K9's audio circuitry is fully balanced, with differential signal inputs to separate left and right channel circuits, from the DAC to the volume control and headphone amplifier. The audio circuitry is divided into six blocks: DAC, low-pass filter, volume control, buffer amplifier, preamplifier, and headphone amplifier. Each block has been meticulously designed to deliver the powerful sound you expect from a desktop device, while maintaining the exquisite detail. Furthermore, by separating and optimizing the layout of each major processing section on the circuit board, adverse mutual interference is minimized, enabling high-quality music playback with high signal fidelity.

[Equipped with the "THX-AAA 788+" headphone amplifier circuit, jointly developed with THX] The K9 features the "THX-AAA 788+" amplifier circuit, which features high-quality feedforward technology to correct distortion that occurs during signal amplification. This amplifier circuit, jointly developed by FiiO and THX, is based on the "THX-AAA 788" circuit, which was designed with the ideal of delivering highly transparent, pure sound. The K9 features two of these amplifier circuits, one per left and one per channel, achieving low distortion of less than 1% and high output power of up to 2000mW into a 32Ω load and up to 780mW into a 300Ω load. " [Equipped with XMOS's "XUF208" and two ultra-high-precision crystal oscillators] The K9 uses XMOS's "XUF208" USB decoding chip. This chip enables PCM decoding at up to 768kHz/32-bit and DSD decoding at up to DSD512. Dual clock management technology constantly selects the optimal clock for the input source, enabling high-quality D/A conversion with exceptional signal fidelity. [Clean power supply design: the source of high-quality sound] The K9's internal power transformer, combined with four 4700uF high-capacity capacitors, provides a clean power supply to the internal audio circuitry. Separate power supplies for the digital and analog sections also suppress power supply noise that can adversely affect sound quality and minimize mutual interference between each block. Furthermore, each circuit block is kept clean by a low-noise LDO, and each receives the appropriate amount of boosted power. This thorough power supply design delivers a high S/N ratio and rich sound reproduction. Equipped with ADC volume control for precise volume adjustment: The K9 features an ADC volume control function for volume adjustment. Unlike analog volume controls, which directly manipulate a variable resistor through a music signal, this method controls the volume IC based on the analog-to-digital conversion value of the volume knob's rotation. While providing 120 levels of precise volume adjustment, it successfully eliminates the left-right volume difference and noise that are common problems with analog volume controls.