Question about Optoma CinemaX P2

It depends on the expectations. The sound is largely sufficient for most uses: classic films, news reports, TV shows/discussions/newspapers. If you want the big blockbusters like Marvel or big video games it will be a bit tight but still sufficient. In any case, in my house, it's fine. Otherwise you connect your hi-fi system and it's all good.
My criticism is rather about this little black remote control where you can't see anything in the dark and where the buttons are placed in completely absurd places... go for it, the device is great!

The speaker is not bad, but not too great either. The projector operates very quietly and I am happy with the quality of the picture. The biggest problem I have is that it's not recognized as a projector by Chromecast, so it's not possible to turn it on/off from the phone. The AV software of the projector itself simply sucks.

Yes, the sound is not good for a film. It sounds tinny. I need it for the office, where it is sufficient without additional speakers. At home I would buy separate Bluetooth speakers... You can't hear the fan.