• Bring Vinyl Into Your HiFi System: Built for MM turntables, T4 PRO boosts the cartridge's low-level signal and applies RIAA equalization before sending them through stereo RCA to an amp or active speakers. A dedicated GND terminal helps keep grounding simple and hum under control. 
• Bring Out Richer Tube Tone: Dual GE military-grade tubes add warmth, body, and natural texture, while a low-noise circuit and ≥105 dB SNR help keep the background clean. Vocals stay clear, instruments remain well defined, and the music gains a fuller, more inviting tube character.  
• Enjoy More Ways to Listen: When you're not spinning records, the AUX input turns T4 PRO into a tube preamp for phones, PCs, and CD players. Its built-in headphone amp drives 32–300Ω headphones directly, bringing tube character to everyday sources and adding an easy option for personal listening.  
• Explore More Tube Sounds: Replaceable tubes let you try different tonal flavors and find the character you prefer. Compatible types include 5654, 6AK5, EF95, 403B, 5725, 6BA6 and more, giving tube enthusiasts plenty of room to experiment.  
• Built Compact with Lasting Quality: A CNC aluminum chassis keeps T4 PRO compact and sturdy, while heat-resistant ceramic sockets keep tubes secure through long sessions and tube swaps. The polished-rim aluminum knob adds a substantial feel with smooth stepless volume control.

• Brand: Douk Audio
• Model: T4 PRO
• Audio Inputs: MM Phono / 3.5mm AUX
• Audio Outputs: Stereo RCA / 3.5mm Headphone
• Output Level: 1.5V
• Input Sensitivity: 0.775V
• AUX Frequency Response: 20 Hz–20 kHz (±0.3 dB)
• Phono Response: Conforms to RIAA Characteristics (±3 dB)
• SNR: ≥105 dB
• THD: 0.2% @ 1 kHz
• Headphone Output Power: 150 mW @ 32Ω
• Supported Headphone Impedance: 32–300Ω
• Input Voltage: DC 12V / ≥1.5A
• Dimensions (W × D × H): 95 × 117 × 30 mm / 3.74 × 4.61 × 1.18 in
• Net Weight: 300 g / 0.73 lb
• Package Dimensions (W × D × H): 215 × 255 × 65 mm / 8.46 × 10.04 × 2.56 in
• Package Weight: 600 g / 1.23 lb

User Manual of the Douk Audio T4 PRO

FAQs

Q: My turntable has a built-in phono preamp. How do I connect it to the T4 PRO?
A: If the turntable signal has already passed through a built-in phono preamp, connect it to the T4 PRO AUX input, not the PHONO input. Connecting a preamplified signal to PHONO may overload the input and cause distortion or possible damage. 

Q: How do I switch between MM Phono and AUX?
A: The 3.5mm AUX input takes priority whenever an AUX cable is plugged in. To use the MM Phono input, simply unplug the AUX cable.

Q: Can the RCA and headphone outputs work at the same time?
A: Yes. The stereo RCA and 3.5mm headphone outputs can work simultaneously, and the main volume knob adjusts both outputs at the same time. 

Q: What power supply should I use with the T4 PRO?
A: We recommend using the included power adapter. Power requirement: DC 12V / ≥1.5A. Insufficient current may cause unstable operation or degraded audio performance, while voltage above 12V may damage the T4 PRO.

Q: What replacement vacuum tubes can I use with the T4 PRO?
A: The included tube brand and model may vary by production batch; please refer to the tubes supplied with your unit. Compatible replacement tubes include 5654, 6AK5, EF95, 403B, 5725, 6BA6, 6K4, 6J1, 6J2, 6J3, 6J4, 6J5, 6Ж1Н, 6Ж4Н, and 6Ж5Н.

Q: At very low volume, the left and right channels sound slightly unbalanced. Is this a malfunction?
A: This is normal. The T4 PRO uses a mechanical carbon-film potentiometer, a traditional volume control method with minimal sound quality loss. When driving high-sensitivity speakers, slight channel imbalance may occur at very low volume levels due to inherent component tolerance. To avoid this, lower the volume on the source device and raise the volume on the T4 PRO slightly to move away from the minimum volume range.