《Condition》
**Used**
An item that has been used previously. The item may have some signs of cosmetic wear, but is fully operational and functions as intended. This item may be a floor model or store return that has been used. See the seller’s listing for full details and description of any imperfections.
The Douk Audio U4 is a multi-functional HiFi audio device featuring Bluetooth 5.0 and USB input, stereo RCA, 3.5mm AUX, and 3.5mm headphone jack output. It can be used not only as a Bluetooth receiver, USB DAC, and headphone amplifier, but also as a preamplifier for devices such as smartphones, computers, power amplifiers, and active speakers.
Using classic 6N3 vacuum tubes (far superior to 6J*), it effectively eliminates harsh digital sounds, allowing you to enjoy the clear, soft, smooth, warm, and sweet sound characteristic of vacuum tubes. The soundstage is wide, making it particularly suitable for vocals, string instruments, light music, and classical music.
High-end components and unique design: Bluetooth 5.0 (QCC3008 chip) supports APT-X and APTX-LL, and with the addition of a TDA1543 chip and an external high-gain detachable antenna, it ensures low-latency and lossless audio transmission.
This USB sound card component uses a 2704 chip and is compatible with Windows/Mac/Linux systems and Android smartphones with OTG functionality. No drivers, plug-and-play functionality, or other features are required.
The headphone amplifier uses a MAX9722 decoding chip and can drive most 16-600 ohm headphones with a 300mW output.
2022/04/12: The USB chip will be changed to 2704, and the Bluetooth chip will be changed to 3003.
Please note: The latest version uses the 2704 chip and supports up to 16-bit 96kHz.
Audio input: Bluetooth 5.0 / USB
Audio output: Stereo RCA / 3.5mm AUX / 3.5mm headphone jack
Bluetooth chip: QCC3008
Decode chip: TDA1543
USB chip: 2704
Headphone amplifier chip: MAX9722
SNR: ＞ 99 dB
Dynamic range: ＞ 99 dB
Ampere-rated output: 300MW
Amplifier impedance: 16-600Ω
Distortion: THD + N: 0.004% (RL ＞ 10kΩ)
Dimensions (L * W * H): 97 * 77 * 32 mm
Weight: 250g
Package weight: 470g
packing list:
1 * U4 Headphone Amplifier
1 * 6N3 tube
1 * 12V power adapter
1 * USB cable
1 * Bluetooth antenna
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