: Being your first projector, that is really taking a leap. You are limited to a 120" screen at most with a 12' throw--maybe even a 100" screen depending on your mounting requirements. That will be bright. Not sure why you didn't consider the UHD51A, which would have been plenty bright enough with the same features, and possibly better contrast?? All said and done, first mount it and show it on a wall to get the right perspective and size. If your wall is not white, then hang a white sheet up. You will have some brightness control simply by using Cinema mode and turning the brightness and contrast way down. But that will be limited as you begin to lose control over color and contrast at low levels. I say go for a grey screen with less than 1.0 gain. Maybe a .8 gain. A grey screen will give you better contrast and control the light.
That considered, you have a long cable length and need to get a cable that can handle 18 gb speed, and 4K 60hz (NOT just 4K 30hz) HDR and 2.0 compliant hdmi or better. I had to go through several cables for my Benq TK800, which needed a 25ft cable and is probably as bright as the ALV. If you don't go directly to the projector ala an audio receiver, it too needs to be 4K 60hz compliant hdmi. I can't emphasize enough the need for a good cable. If you don't have a good cable, you will have constant sync issues with signal flashing and recovering now and then.
I went through several cables and found this one that finally worked, and it was surprisingly cheap. Price does not always indicate quality with these cables. I spent a lot more on my first two cables: https://www.amazon.com/gp/product/B008U7SL4C
.While you might not need a cable to support gaming, make sure that it does anyway, like Xbox, PS4, ARC, etc., reason being if they work, everything usually works like streaming 4k devices, etc.