The plates come in various sizes, normally they hold 2 or 4 modules. If you want 3 then buy a 4-gang plate, 3 modules and a blankSo, I guess you buy the little switches, say one for a tv aerial, maybe two for Ethernet (one for pc, one for xbox) and then you buy the right size to accommodate whatever you are putting in?
Simples!
A little late joining in here, but I really can't emphasize enough the suggestion to forget about running everything on wireless and to install Ethernet cabling to points wherever you think you might need them while the rest of the rewiring is being carried out. It will be far easier and neater (not to mention cheaper) to do it now than to come back in a couple of years after you've decorated the whole house and try to do it. You'll end up with a far more reliable, and secure, network if you abandon the wireless networking altogether.
Well you can bury HDMI leads in the walls, and have one end come out behind your tv cabinet and (assuming the tv is wall mounted) the other end comes out behind the tv.
I would wire an ethernet point to where each sonos lives as well, I know they're wifi, but much better to have them hardwired. Have a socket put directly behind the Sonos too, that way you can have the cables all cable tied up nice and tidy, and just use a short patch lead to connect to the wall plate.
Think about getting a chromecast (or similar) to send video from your laptop to the TV, so you don't need to hook it up with an HDMI cable.
Anything is possible. The AV world is quite complex, and fast changing. Suggest you spend some time and think very carefully about what you need to connect up, both now and in the future. Planning now is much easier than adding stuff you have forgotten later on after the plaster and paint has dried.
Although us electricians can give you some overall general advice, you could ask more complex questions on the DIY.NOT AV forum. They have their noses closer to the AV road.
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