Fosi Audio P3


Headphoneus Supremus
Nice desktop pre-amp/hp amp with turning controls
Pros: Line In
RCA Pre out/Aux out
Bluetooth 5.1
Low latency
Tube rolling
The Fosi Audio P3 is a Tube based pre-amp/amplifier with the option to customize your sound using the treble and bass controls. In side of the box, The P3 it self, Bluetooth antenna, pair of GE JAN 5654W tubes, the manual and the power brick.


On the front of the device, you will see a Treble, Volume, Bass knob and the Source switch along with the 3.5mm Headphone port. On the rear, There's a Line in, RCA out, Aux out, power plug, Bluetooth connector and finally a pin hole to reset the Bluetooth connection.

The over all size of the P3 is quite small, as it takes up less room, which is useful when you don’t have a lot of room to use. Its small enough to be placed into an entertainment center or even an end table.

Plugging in the tubes are straight forward, make sure the pins lines up with the connection holes on the tube plug and plug it in. I had a bit of a problem getting the tubes in, since the cut out opening was small, so I couldn’t see if the pins where lined up or not, evidently I got it connected.

P3 can function as a headphone amp, when paired with an external Dac connected to its RCA in, The other option is Bluetooth. The P3 can function as a Bluetooth receiver due to the QCC3031 chip that it uses. The codec’s that it supports are SBC, AAC, APTX/HD and LL. When you set the input to Bluetooth, it starts searching for a device.

When I connected to my phone, I didn’t have an issue. I when I watched a couple of videos and some Netflix shows, There might been a bit of audio delay. But over all I didn’t notice it as to me the audio lined up with the characters talking. I also tried the same with my PC in BT, I was shocked usually that issue happens for me, I watched many videos, and I didn’t have audio lag with my PC as a BT source.

One of the main points to the P3 is being able to control how much treble you want or bass, by default both they’re set to 0. When you twist either of them, you will get a click feel when you reach the center setting. before going past it, moving it all the way to the right will set them to the max setting.

Headphone amp spec of the P3 is 250mw @ 16 Ohm, 150mw @ 32 Ohm, 32 mw @ 250 Ohm and 20mW for 300Ohm. I did run into an issue with the Volume, at very low setting, only one sides play audio, til you raise the volume higher, then both sides play. The problem is by that point the volume knob is a bit away from being too loud, This effect both my Hifiman HE-R9 and my ER2SE IEM.


When using my HE-R9 I found that I prefer the bass knob set to middle position. If I kept the bass to the lowest then every thing would be thin. If I raised the bass pass mid, it’s only a tad boomy, but if I raise it too much to around 4 o clock position it starts to Too boomy. For the treble I found that I prefer to keep it at lowest setting. Any higher and the details will start to be too much for me. Even with the treble set the lowest, I still heard the details in songs. It wasn’t bright at all, as long I used the lowest knob setting.

The sound stage sounds like its outside my head, like its spread out. With the instruments having good separation, They don’t overlap each other and can be heard clearly. Singers give me a feel as if there on stage, While there back ground singers are on the sides of them. There isn’t any thing else I can say, its all sound good to me.


I liked the Fosi Audio P3, I didn’t have major issues with it, just the minor volume issue I mentioned, but i could be nit picking. Other then that no other issues.


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I just bought one. Hopefully it’ll be here in a few days. How’s it been treating you?