DoukAudio K5 DAC Amp Headphone Amplifier User Manual

1. Introduction

The Douk Audio K5 is a versatile USB DAC and Headphone Amplifier designed to enhance your audio experience. It features both USB and SPDIF optical inputs, along with optical, RCA, and 6.35mm/3.5mm jack outputs. The K5 functions as a high-performance headphone amplifier, a USB DAC, a preamplifier, and a USB to optical converter, allowing high-quality audio transmission from your computer to various audio devices such as CD players, amplifiers, and active speakers.

2. Package Contents

Please check the box for the following items:

• 1* K5 DAC
• 1* Power Adapter (DC 5V)
• 1* USB Cable (Type-A to Type-C)
• 1* Optical Cable
• 1* User Manual

Figure 2.1: Contents included in the Douk Audio K5 package.

3. Product Features

• Versatile Connectivity: Features USB and SPDIF optical inputs, along with optical, RCA, and 6.35mm/3.5mm jack outputs. Functions as a headphone amplifier, USB DAC, preamp, and USB to optical converter.
• High-End Chipset: Utilizes ESS9038Q2M (DAC), SA9312 (DSP), OPA1678 (LPF), and SGM8262 (amp) op-amps for superior audio performance.
• High-Resolution Audio Support: Supports PCM 32bit/384kHz high-resolution decoding and DSD256 playback.
• Exceptional Audio Quality: Achieves a Signal-to-Noise Ratio (SNR) over 121dB, a low noise floor of only 3µV, and an incredibly low Total Harmonic Distortion (THD) of 0.0007%.
• Powerful Headphone Output: Supports dual 6.35mm/3.5mm headphone outputs with robust power of 560mW/470mW@32Ω per channel, suitable for headphones with impedance from 16Ω to 600Ω.
• High/Low Gain Modes: Offers flexible high and low gain modes to adapt to various headphone impedances and customize listening experience.
• Tone Control with Bypass: Includes treble and bass controls with midpoint positioning. A bypass function (PURE mode) allows for the purest sound without tone adjustments.
• Flexible Power Options: Can be powered directly via USB Type-C with sufficient current, or through an external power port. Includes a 2-in-1 USB cable (Type-C and USB-A).
• User-Friendly Design: Integrated volume and power button, one-click switches for input, tone, and gain. Colorful LED indicators show current working mode and sampling rate. Compact and durable aluminum alloy body.

4. Product Overview

Figure 4.1: Front view of the Douk Audio K5, showing headphone outputs, gain, tone, and input switches, along with volume/power knobs.

Figure 4.2: Detailed diagram of the Douk Audio K5's front and rear panels, highlighting all inputs, outputs, and controls. This includes 6.35mm and 3.5mm headphone jacks, gain switch, tone/pure switch, USB/SPDIF input switch, volume/power knob, treble and bass knobs on the top. The rear panel shows RCA line out, SPDIF optical out, SPDIF optical in, USB-C in, and DC 5V power input.

Figure 4.3: The Douk Audio K5 demonstrating its compact size and multiple functionalities, including Headphone Amp, USB DAC, USB to SPDIF Adapter, and Audio Preamp, suitable for various desktop audio setups.

Figure 4.4: The Douk Audio K5 connected to a laptop and external speakers, illustrating its capability to transmit high-quality audio from USB to high-end audio systems via its optical output, supporting both active speakers and power amplifier with passive speakers.

Figure 4.5: The Douk Audio K5 with headphones connected to both 6.35mm and 3.5mm outputs, emphasizing its compatibility with headphones ranging from 16Ω to 600Ω impedance, and the presence of high/low gain settings for optimized listening.

Figure 4.6: A close-up view of the ESS9038Q2M DAC chip, highlighting the premium chipset used in the Douk Audio K5, which contributes to its ultra-pure sound and audiophile-grade parameters like low noise floor, THD, and high SNR.

Figure 4.7: Illustration of the treble and bass tone controls with midpoint positioning, and the "Pure" bypass switch on the Douk Audio K5, allowing users to fine-tune or bypass tone adjustments for original sound fidelity.

5. Setup Guide

5.1 Power Connection

1. Connect the provided DC 5V power adapter to the "DC 5V IN" port on the rear panel of the K5.
2. Plug the power adapter into a suitable wall outlet.
3. Alternatively, for sufficient current, you can power the K5 directly via the "USB C IN" port using the provided USB-A to USB-C cable connected to a computer or a compatible USB power source.

5.2 Audio Input Connection

Choose one of the following input methods:

• USB Input: Connect your computer or other USB audio source to the "USB C IN" port on the rear panel using the provided USB-A to USB-C cable.
• Optical Input (SPDIF IN): Connect an optical cable from your audio source (e.g., TV, game console, CD player) to the "SPDIF IN" port on the rear panel.

5.3 Audio Output Connection

Choose one or more of the following output methods:

• Headphone Output: Plug your headphones into either the 6.35mm or 3.5mm headphone jack on the front panel.
• RCA Line Out: Connect RCA cables from the "LINE OUT" (R/L) ports on the rear panel to your amplifier, active speakers, or other audio receiving devices.
• Optical Output (SPDIF OUT): Connect an optical cable from the "SPDIF OUT" port on the rear panel to a device that accepts optical input, such as a DAC, amplifier, or active speakers.

6. Operating Instructions

6.1 Power On/Off and Volume Control

• The large knob on the top right of the unit controls both power and volume.
• To power on, rotate the knob clockwise until you hear a click and the LED indicators illuminate.
• Continue rotating clockwise to increase volume; rotate counter-clockwise to decrease volume.
• To power off, rotate the knob counter-clockwise until you hear a click.

6.2 Input Selection

• Use the "USB/SPDIF" toggle switch on the front panel to select your desired audio input source.
• Switch to "USB" for audio from the USB-C input.
• Switch to "SPDIF" for audio from the optical input.

6.3 Gain Control

• The "GAIN" toggle switch (H/L) on the front panel adjusts the output gain for headphones.
• Select "H" (High) for higher impedance headphones or when more power is needed.
• Select "L" (Low) for lower impedance headphones or when less power is sufficient.

6.4 Tone Control and Bypass

• The "TREBLE" and "BASS" knobs on the top panel allow you to adjust the tone.
• The "Tone/Pure" toggle switch on the front panel allows you to enable or bypass the tone controls.
• Switch to "Tone" to enable the treble and bass adjustments.
• Switch to "Pure" to bypass all tone controls and enjoy the purest, unaltered sound.

6.5 LED Indicators

• The front panel features LED indicators for DSD and PCM sampling rates.
• These LEDs will illuminate to indicate the current audio format and sampling frequency being processed by the DAC.

7. Maintenance

• Keep the device clean by wiping it with a soft, dry cloth. Avoid using harsh chemicals or abrasive materials.
• Ensure proper ventilation around the unit to prevent overheating.
• Avoid exposing the device to extreme temperatures, humidity, or direct sunlight.
• Disconnect power before cleaning or when the device will not be used for an extended period.

8. Troubleshooting

9. Specifications

10. Official Product Videos