FiiO K19 Studio-Grade Flagship DAC and Headphone Amplifier

The FiiO K19 is FiiO’s studio-grade flagship desktop DAC and headphone amplifier. Two ESS 8-channel ES9039SPRO DACs, an 8-channel THX AAA 788+ amplifier delivering up to 8,000mW (8W) per channel, an 800MHz ADI DSP with a 31-band lossless PEQ and, for the first time in a FiiO product, a quad-core FPGA at the heart of its digital processing. It is also FiiO’s first desktop DAC/amp with HDMI and HDMI ARC, so it connects to a TV, games console or computer, and its ultra-thin die-cast body stands upright as a headphone stand or lies flat. Its awards include an EHA 2024 Gold Award, Headfonics Writer’s Choice 2024 and a VGP 2025 Summer Gold Award for pure audio.

Dual ESS ES9039SPRO DACs

Inside the K19 are two of ESS’s 8-channel ES9039SPRO DAC chips, one for each channel. Their fourth-generation 32-bit HyperStream architecture achieves ultra-high dynamic range with ultra-low noise, so the K19 outputs clearer, richer audio with plenty of detail.

8-channel THX AAA 788+ amplifier: 8,000mW per channel

The headphone amplifier is a new design: eight THX AAA 788+ channels working together in parallel, backed by a high-voltage power supply. Connected in 2 × 2 groups, they form a fully balanced, four-channel amplification system, for enhanced transients and up to 8,000mW + 8,000mW into 32Ω from the balanced outputs (1,100mW per channel into 300Ω), enough to drive all kinds of headphones with ease. Five gain levels run from −9dB (low) through −3dB (medium), 0dB (high) and +10dB (super high) to +13dB (ultra high); at super and ultra high gain the THX supply switches from 12V to 14.5V.

Fully balanced design

The signal stays fully differential from the dual DACs through I/V conversion and low-pass filtering to the balanced headphone amplifier, for high dynamics and minimal crosstalk. The I/V, filter and preamplifier stages use multiple precision op-amps, including the OPA2211 and OPA1602, for stable, high-quality sound.

Quad-core FPGA and global clock management

For the first time in a FiiO product, a powerful quad-core FPGA is the K19’s high-definition digital signal processing centre. It handles every incoming digital signal, including Bluetooth reception and decoding, USB, coaxial, optical and HDMI/ARC decoding, and DSP processing, and sends the result to the dual ES9039SPRO DACs over two sets of I²S channels, for minimal distortion and loss in the digital chain. Clocks are managed globally, so every digital signal is handled with low jitter for purer, clearer sound.

Two industry-leading ACCUSILICON AS318-B ultra-low phase noise femtosecond oscillators (45.1584MHz and 49.1520MHz), 100% pre-screened before being fitted, reduce the effect of phase noise on the signal for accurate reproduction at every sample rate, and purer, more stable sound whatever the source.

An 800MHz ADI DSP and a 31-band lossless PEQ

Also a first for FiiO, the K19 uses an ADI ADSP-21565 DSP chip with a SHARC+ core, backed by its own custom ultra-low phase noise femtosecond oscillator. Running at 800MHz with 64-bit double-precision floating-point calculation, it makes the 31-band high-precision lossless PEQ possible, keeps the signal high-quality with minimal distortion after adjustment, and powers system protection that safeguards the K19 and the headphones and equipment connected to it.

FiiO’s DEL (Dual Engine Limiter) technology and its own algorithms add dynamic range compression (DRC) and enhancement (DRE) and an advanced limiter to prevent clipping. The PEQ works directly on PCM from 44.1kHz to 192kHz without sample-rate conversion, and each band offers gain from +12 to −24dB and a Q from 0.4 to 128. Presets can be imported, exported and shared with other users. Adjust it with FiiO’s DSP software on a Windows or Mac computer (or the web PEQ) connected to the rear RS232 port, or in the FiiO Control app; the K19 itself offers 17 EQ settings (Jazz, Rock, R&B, Hip-Hop, Pop, Dance, Classical and 10 custom). The EQ works in every input mode on the headphone and line outputs, but not on the coaxial and optical outputs, and as it is done in hardware, the sound mutes for about a second when you switch it on or off.

HDMI and HDMI ARC: a new direction for hi-fi

The K19 is FiiO’s first desktop DAC and amplifier with HDMI. HDMI IN decodes audio up to 192kHz/24-bit from a computer, games console or other source and passes the video through HDMI OUT to your screen. HDMI ARC takes the audio return channel from a TV at 44.1 or 48kHz (usually 48kHz), for an immersive audiovisual experience.

Six inputs, eight outputs

• USB: an XMOS XU316 plays PCM up to 768kHz/32-bit, native DSD512 and MQA from a computer or phone, through the front or rear USB-C port (the front takes priority). Macs (and, in principle, Linux) need no driver; Windows 10 and 11 use FiiO’s USB DAC driver; a UAC 1.0 setting suits driver-free devices such as the PS5 and Nintendo Switch.
• Coaxial and optical in: up to 192kHz/24-bit and DSD64 over coaxial, and 96kHz/24-bit over optical.
• HDMI and HDMI ARC: up to 192kHz/24-bit, and 44.1/48kHz from a TV.
• Bluetooth: a Qualcomm QCC5125 Bluetooth 5.1 receiver with LDAC, aptX Adaptive, aptX HD, aptX LL, aptX, AAC and SBC.
• Headphone outputs: 6.35mm single-ended, 4.4mm balanced and 4-pin XLR balanced on the front.
• Line and digital outputs: RCA (2.5Vrms) and XLR balanced (4.8Vrms) line outputs, plus coaxial (192kHz/24-bit, DSD64), optical (192kHz/24-bit) and HDMI out.

Four analogue output modes cover every set-up: PO+PRE (the default) for headphones and the rear outputs together, PO for headphones only, PRE for a volume-controlled feed to active speakers or a power amplifier, and LO for a fixed-level feed to an amplifier with its own volume control. The coaxial and optical outputs are always on, at a fixed level. The three headphone sockets work at the same time, but FiiO advises against using two pairs for long, especially with very different impedances.

Ultra-thin die-cast unibody

The K19’s new styling is built on a seamless, die-cast aluminium alloy unibody, polished by multi-axis CNC machining to a finish befitting a flagship. The body is ultra-thin (36.7mm) and shock-proof, and with the included stand it stands firmly upright.

Separated, shielded circuit boards

The digital and analogue circuits sit on separate boards for full isolation and greatly reduced interference. The DSP, DAC and THX headphone amplifier boards have their own metal shields, and the digital and module boards are isolated in aluminium alloy compartments, minimising crosstalk for a pure signal. The honeycomb-mesh aluminium body helps keep out external interference too. Four sets of silver-plated oxygen-free copper cables carry the audio between boards with minimal loss.

A carefully designed power supply

A new-generation 40W industrial-grade power supply is built in: low noise, highly efficient and long-lasting, it accepts an ultra-wide 85–305V AC input, works from −40°C to 85°C and is rated for around 500,000 hours. A switch on the back selects an external DC supply instead (15V, at least 3A), so you can pair the K19 with a high-performance linear supply for a different sound. The digital and analogue circuits have separate supplies for better isolation, and the analogue circuit has a multi-stage supply, with power control for the DAC, low-pass filter, preamplifier and headphone amplifier stages and many precision LDOs for continuous, clean power.

Audiophile-grade components

Eight Panasonic film capacitors and 36 MELF resistors keep noise and temperature drift low, for stable, high-quality sound in any conditions. Four WIMA and four ELNA SILMIC II capacitors enhance the sound and soundstage, and tulip-shaped, gold-plated NEUTRIK connectors resist oxidation and wear for precise, reliable connections.

Cool under pressure

Inside, thermally conductive material in contact with the chips carries their heat to the aluminium alloy frame; outside, the honeycomb-mesh body lets air flow through by convection. Together, the internal and external cooling let the K19 deliver high power continuously without heat worries.

Upright or flat, and easy to control

Stand the K19 upright to save space and help it shed heat, where it doubles as a unique headphone stand, or lay it flat on its feet. The 1.3-inch fully laminated colour screen (240 × 240) shows the volume, gain, output and working mode, format, sample rate and EQ. Dual indicator lights on the volume knob show the sample rate (blue for 44.1/48kHz, yellow for higher PCM rates, green for DSD and magenta for MQA) or, in Bluetooth mode, the codec. Press the volume knob to turn the screen off or on, or hold it to switch off; the menu knob changes inputs and settings. The included infrared remote switches modes, selects EQ and adjusts the volume from across the room, and the FiiO Control app adjusts its functions from your phone.

Ready for a bigger system

A 12V bidirectional trigger (3.5mm in and out, with active and passive modes) switches the K19 on and off in sync with other 12V-trigger equipment; the input responds to 5–15V and the output supplies up to 60mA, and a short built-in delay prevents false triggering. A GND/LIFT ground switch reduces crosstalk and interference between devices.

Good to know

• The K19 has no network streaming; for Roon Ready and AirPlay in a desktop DAC/amp, see the FiiO K17.
• For external DC power, use a 15V supply of at least 3A with a 5.5 × 2.1mm centre-positive plug. The K19 accepts 10–16V and disconnects a supply outside that range.
• Which headphone output is best? FiiO says the 4.4mm and XLR4 balanced outputs are much the same and have more power than the 6.35mm socket, and recommends trying each with your headphones.
• Only the included infrared remote is supported.
• In the box: K19, AC power cord, stand and vertical headphone-stand support, feet, screwdriver and screws, metal XLR4 dust cover (fitted), USB 2.0 and dual Type-C cables, Type-C to USB-A adapter, 6.35mm adapter, 3.5mm trigger cable, remote control, quick start guide and warranty card.