User Manual & Driver of Douk Audio U3 PRO

Warm tips:

• Without DC 5V power adapter, please prepare an original high-quality power adapter yourself (DC 5V ≥1A). Note: the input voltage over 5V will result in damage.
• The U3 PRO won't work well if the current of power adapter is below 1A.
• The 3.5mm and 6.35mm headphone jack can output at the same time. Please don't use RCA and AUX input at the same time, otherwise audio mixing will be caused.

• Enhanced Compatibility: with 3.5mm AUX/stereo RCA input and 3.5mm/6.35mm headphone jack output, the U3 PRO is compatible with a wide range of audio sources, including MP3 players, iPods, smartphones, tablets, computers, and CD players etc. Its output can connect to various headphones, offering a versatile listening experience with support for most headphone models.
• Built-in Voltage Boost Circuit: adopting innovative circuit design with built-in voltage boost circuit, the amplifier circuit can always work at a high voltage of ±14V even only powered by DC 5V, and the background noise index is excellent. With wide frequency response extension, excellent transient response, excellent purity and transparency, and good dynamic range.
• Exceptional Output Power: for a total power output of up to 1500mW under a 32Ω load, U3 PRO can easily power headphones with any low or high impedance (18-600Ω). Working in class A status, with ultra-low distortion, the sound is warm and delicate, full and mellow with outstanding sound quality.
• Classic OP+BUF Architecture: U3 PRO adopts OP42 and BUF634, featuring a pure DC amplification circuit. Pluggable op amp socket design, OP42 can be replaced by OP17, AD797, AD843, AD847, and OPA627, convenient to upgrade different op amps and bring much DIY fun and playability for audiophiles.
• Highly Cost-Effective: mini size with exquisite appearance, brings big surprise for all audiophiles, easily to drive most headphones in the market, providing larger power, better sound field and details, very suitable for home/office desktop audio system use.

• Audio input: stereo L/R RCA, 3.5mm AUX
• Audio output: 3.5mm/6.35mm headphone jack
• Output power: ≥1500mW (32Ω)
• Matched headphone impedance: 18-600Ω
• Max output amplitude voltage: ±14V
• Frequency response: 20-30KHz
• SNR: ≥110DB
• Input voltage: DC 5V(≥1A)
• Dimension(W*D*H): 68*92*32mm/ 2.68*3.62*1.26in
• Net weight: 164g / 0.36lb
• Package weight: 300g / 0.66lb