Dual ES9039Q2M DAC and headphone amplifier

The FiiO K13 is a desktop DAC, headphone amplifier, and preamplifier built around dual ESS ES9039Q2M DACs and a fully-balanced audio architecture. It supports PCM up to 32-bit/768kHz and DSD512 over USB, delivers up to 2400mW + 2400mW into 32Ω from its balanced headphone output, and adds Bluetooth 5.4 with LDAC, 10-band PEQ with Auto EQ, flexible digital connectivity, and AC or external DC power.

Dual ES9039Q2M DACs

Two ESS ES9039Q2M DACs handle digital conversion, using ESS fourth-generation 32-bit HyperStream architecture. The DAC stage is rated for 130dB DNR and -120dB THD+N at the chip level, providing a capable foundation for high-resolution playback.

Fully-balanced amplifier architecture

The K13 uses fully differential signal processing across the DAC, I/V conversion, low-pass filter, preamp buffer, and headphone amplification stages. OPA1656 op-amps handle I/V conversion, OPA1642 op-amps are used in the LPF and headphone amplifier stages, and TPA6120A amplifiers provide dedicated left- and right-channel headphone amplification. Gain control, pop-noise suppression, and headphone protection circuitry are integrated into the design.

Up to 4800mW of balanced output

The 4.4mm fully-balanced headphone output delivers up to 2400mW + 2400mW into 32Ω in high gain. Into 300Ω, it provides up to 600mW + 600mW. A 6.35mm single-ended output delivers up to 1220mW + 1220mW into 32Ω or 150mW + 150mW into 300Ω, giving the K13 output options for a broad range of IEMs and full-size headphones.

Three gain levels and independent volume memory

Low, medium, and high gain settings provide three independent volume curves for matching the K13 to different headphone sensitivities and power requirements. Headphone output and preamp volume levels can also be memorized independently, reducing adjustment when moving between headphones and a connected speaker system or power amplifier.

High-resolution USB decoding

An XMOS XU316 USB interface supports PCM playback up to 32-bit/768kHz and DSD512. Coaxial input supports up to 24-bit/192kHz and DSD64, while optical input supports up to 24-bit/192kHz. The K13 can also provide coaxial digital output up to 24-bit/96kHz when operating in USB mode.

Bluetooth 5.4 with LDAC

Bluetooth 5.4 reception supports LDAC, AAC, and SBC codecs for wireless playback from compatible phones, tablets, and computers. LDAC support provides a higher-bandwidth option for compatible Bluetooth sources while retaining the convenience of wireless input.

10-band PEQ and Auto EQ

The XMOS XU316 platform supports a specially developed 10-band parametric equalizer across the K13's operating modes. FiiO's Auto EQ function can apply a target headphone curve, with further manual adjustment available through the FiiO Control app. A web interface is also available for PEQ adjustment when using USB input with EQ enabled. PEQ processing supports audio signals up to 24-bit/192kHz.

DAC, headphone amp, and preamp in one desktop component

USB, optical, coaxial, and Bluetooth inputs allow the K13 to serve as the digital hub of a desktop audio system. Headphone, balanced XLR, RCA line, preamp, and coaxial digital output options extend its role beyond headphone listening, including connection to power amplifiers and active speakers. Output modes include PO, PRE, PO+PRE, and LO.

AC and DC power options

A built-in 30W AC power module supplies the K13 directly from mains power. An external 12V/2.5A DC input provides an alternative for use with a compatible external power supply. Internally, a multi-rail power architecture uses up to 18 low-noise LDO regulators and five DC-DC converters, with dedicated regulation for analog and digital circuitry.

Selected audio components

The analog and power sections incorporate four ELNA RA3 series silk-film audio capacitors, eight WIMA film capacitors, and 24 low-temperature-drift MELF resistors. Two ACCUSILICON AS318-L femtosecond crystal oscillators operating at 45.1584MHz and 49.1520MHz provide clocking for the digital audio section.

Custom LCD and adjustable RGB lighting

The front-panel LCD displays information including sampling rate, volume, gain, input, and output mode. Adjustable RGB lighting can indicate the current sampling rate, with brightness, color, and pulsing behavior configurable through the FiiO Control app.

Dual-knob and remote control

Two front-panel knobs provide direct access to volume and menu functions. The included infrared remote adds control from across a desk or listening room, while the FiiO Control app provides access to compatible settings over Bluetooth. A configurable 1–99 minute shutdown timer is also available.

Aluminum desktop chassis

The K13 uses a thickened unibody aluminum-alloy enclosure with a circular skylight in the top panel that exposes a view of the internal DAC section. It measures approximately 8.27 × 7.40 × 1.65 inches (210 × 188 × 42mm), including the feet, and weighs approximately 2.12 lb (960g). Black and silver finishes are available.

Protection for desktop use

Overheating and overload protection automatically engage when abnormal operating conditions are detected. The amplifier circuitry also incorporates headphone protection and pop-noise suppression.

Product highlights

• Dual ESS ES9039Q2M DACs
  
• Fully-balanced audio architecture
  
• Up to 2400mW + 2400mW balanced output into 32Ω
  
• 4.4mm fully-balanced and 6.35mm single-ended headphone outputs
  
• PCM up to 32-bit/768kHz and DSD512 over USB
  
• XMOS XU316 USB interface
  
• Bluetooth 5.4 with LDAC, AAC, and SBC support
  
• 10-band PEQ with Auto EQ
  
• USB, optical, coaxial, and Bluetooth inputs
  
• XLR and RCA analog outputs
  
• Preamplifier and line-output modes
  
• Coaxial digital output in USB mode
  
• Three gain levels
  
• Custom LCD display
  
• Adjustable RGB lighting
  
• Infrared remote control
  
• FiiO Control app support
  
• AC and external DC power options
  
• 1–99 minute shutdown timer

Specs

• Colors: Black, silver
  
• Main control chip: ESP32-S3
  
• USB chip: XMOS XU316
  
• DAC: 2 × ESS ES9039Q2M
  
• I/V op-amps: 2 × OPA1656
  
• LPF op-amps: 2 × OPA1642
  
• LO buffer op-amps: 3 × LTA8092
  
• Headphone amplifier: 2 × OPA1642 + 2 × TPA6120A
  
• USB input: Up to 32-bit/768kHz, DSD512
  
• Coaxial input: Up to 24-bit/192kHz, DSD64
  
• Optical input: Up to 24-bit/192kHz
  
• Coaxial output: Up to 24-bit/96kHz, USB mode only
  
• USB connectors: Dual USB-C
  
• Display: Custom LCD
  
• Power input: AC 100–240V, 50/60Hz — DC 12V/2.5A
  
• Dimensions: Approximately 8.27 × 7.40 × 1.65 inches (210 × 188 × 42mm), including feet
  
• Weight: Approximately 2.12 lb (960g)
  
• 6.35mm output at 32Ω: ≥1220mW + 1220mW, THD+N <1%, high gain
  
• 6.35mm output at 300Ω: ≥150mW + 150mW, THD+N <1%, high gain
  
• 4.4mm balanced output at 32Ω: ≥2400mW + 2400mW, THD+N <1%, high gain
  
• 4.4mm balanced output at 300Ω: ≥600mW + 600mW, THD+N <1%, high gain
  
• Frequency response: 20Hz–80kHz, attenuation <2.9dB
  
• SNR: ≥124dB, A-weighted
  
• Noise floor: PO <3µV, A-weighted, medium gain — BAL <4.6µV, A-weighted, medium gain
  
• Output impedance: PO <0.4Ω with 32Ω load — BAL <1Ω with 32Ω load
  
• THD+N: Approximately 0.00034% at 1kHz, -6dB, 32Ω

What’s included

• FiiO K13
  
• Infrared remote control
  
• AC power cord
  
• USB data cable
  
• Headphone adapter
  
• Quick start guide
  
• Warranty card