The Fosi Audio P3 is a genuine tube preamp, with the tube working voltage reaching up to 54V. It features the QCC3031 Bluetooth chip, supporting aptX, aptX HD, and aptX LL audio formats, it comes with RCA out, AUX out, and a 3.5mm headphone jack.

Package Contents​
Operation Guide
Frequently Asked Questions
Warranty Information
About Fosi Audio


Thank you for purchasing the Fosi Audio P3 Tube Preamplifier! 


The Fosi Audio P3 is a genuine tube preamp, with the tube working voltage reaching up to 54V. It features the QCC3031 Bluetooth chip, supporting aptX, aptX HD, and aptX LL audio formats, offering enhanced sound quality and as low as 60ms latency. The P3 comes with RCA out, AUX out, and a 3.5mm headphone jack, perfectly suited for your desktop use, delivering the ultimate auditory experience. The tubes are replaceable, adding to the fun of personalizing your setup. Combined with the glacier-colored light, it feels closer to nature. We believe that technology and nature can coexist harmoniously, and technological innovation can serve to enrich our lives.

① 3.5mm headphone jack

② Volume knob

③Treble knob (±6dB)

④Bass knob (±12dB)

⑤Mode indicator light: RCA mode - steady red light, Bluetooth pairing mode - blue light flashing, Bluetooth connection successful - steady blue light

⑥Power switch/mode selector

⑦Bluetooth reset switch: Hold for 3 seconds to clear Bluetooth pairing

⑧RCA input

⑨RCA output

⑩AUX output

⑪DC 12V power in

⑫Bluetooth antenna port

⑬5654W tubes


RMS Power

250mw @16Ω;150mw @32Ω; 

32mw @250Ω;20mW @300Ω


Headphone Impedance







RCA,3.5mm headphone jack, AUX Out





Dynamic Range




≤ 0.02%


Noise Floor






Frequency Response



Bluetooth Chip



Bluetooth Version



Bluetooth Range



Bluetooth Codecs

SBC/AAC/aptX/aptX HD/aptX LL


Power Input

DC 12V/1.5A~3A

Package Contents​

Fosi Audio P3 Tube Preamplifier × 1 

5654W Vacuum Tube × 2 

12V/1.5A Power Supply × 1 

User Manual × 1

Operation Guide

1. Switch to the OFF position, install the Bluetooth antenna, and then plug the tubes to the sockets. Ensure the pins align with the slots, and then turn the volume to the lowest setting; 

2. Connect the included 12V/1.5A power supply; 

3. Depending on your setup, plug your amplifier, powered speakers, or headphones into the P3's RCA output, AUX output, or headphone jack; 

4. If you opt for a wired connection, use an audio cable to connect your source device to the P3's RCA input terminal; 

5. Switch to either the RCA wired or BT Bluetooth wireless position; 

6. When using Bluetooth, connect to Fosi Audio P3 on your source device; 

7. Adjust the volume and treble/bass to an appropriate level, and you're ready to enjoy your music.


1. As a genuine tube preamplifier, please allow me 15 seconds to preheat the tubes after powering on, and then the sound can be output normally. 

2. Avoid plugging and unplugging cables while the device is powered on to prevent abnormal noises. This can also easily damage the product. 

3. If you need to replace the tubes, please do so when the tubes have cooled down to avoid burns or damage to the product.

Frequently Asked Questions

1. After connecting the product and turning it on, there's no sound during playback? 

Since the P3 is a tube preamp, the tubes require about 15 seconds to preheat before they can operate properly. If there is still no sound after 15 seconds, please check if the cables are connected correctly, if the tubes are properly plugged, and if the correct input mode is selected. 


2. Why is the power indicator light very dim or constantly flashing after powering on? 

A blinking blue light in Bluetooth mode indicates it's awaiting a connection, and the light will remain steady blue once connected. A flashing power indicator light in RCA mode might suggest insufficient power supply. Please ensure you're using a power supply between 12V/1.5A and 12V/3A. 


3. How are the headphone output, RCA output, and AUX output on the Fosi Audio P3 controlled? By default, Fosi Audio P3 prioritizes headphone output, with RCA and AUX outputting simultaneously. This means both RCA and AUX will output signals at the same time; however, when a headphone is plugged in, the signal will switch to the headphone output, and there will be no signal on RCA and AUX outputs.


4. How do I clear the Bluetooth pairing record? 

On the rear panel of the Fosi Audio P3, there's an RST button. Press and hold for 3 seconds to clear Bluetooth pairing. If you're in Bluetooth mode at this time, the indicator light will flash blue. 

If you have any further questions, please contact our support team at support@fosiaudio.com

Warranty and Maintenance

• All Fosi Audio products have an 24-month limited warranty on parts and labor from the date of purchase. Please contact us if you have any problems.

About Fosi Audio​

• Fosi Audio designs and builds innovative audio products with all your music in mind. Great sound, simple but elegant designs, high-quality materials, and truly useful features are what Fosi Audio is about. We sincerely hope you get as much enjoyment from our products as we’ve had to create them!


Our website: www.fosiaudio.com

Amazon store: www.amazon.com/fosiaudio 

Our Youtube channel: Fosi Audio

Our Facebook page: Fosi Audio

WhatsApp: +8613716612254

Call us: +49 33389171782

After-sale Service and Technical Support Email:  support@fosiaudio.com