1. The signal channel commonly used in projectors is HDMI, so you only need to lay an HDMI cable between the projector and the power amplifier. Other analog audio and video cables, component cables and VGA are basically not used, and most computers now have HDMI output; Then through the AV amplifier, the broadcast sources including computers, Blu-ray players, network set-top boxes and game consoles can be transmitted to the projector through this HDMI cable.

2. hivi 5. 1 is ok. Now the most popular sound source on the market is 5. 1, but if you have higher requirements, you can choose a higher level sound. Now there is embedded audio, and the effect is quite good;

3. Generally, most of the 1080P movies you download online for free are 5. 1 channel;

4. Wiring: A power socket is reserved at the projector, a network cable is laid for network connection or intelligent control, and an HDMI cable is laid between the projector and the AV amplifier. If necessary, spare cables can be laid. Considering that the width of your living room is only 3.9 meters, I suggest that your projector be placed directly on the top of the back wall. The AV power amplifier can be directly placed in the TV cabinet, and all audio cables of the speakers are connected with the power amplifier. Blu-ray drives, network set-top boxes and other devices can be directly placed with the power amplifier. The electric reel should be selected for curtains, so it is necessary to reserve a power socket on one side of the curtains;

The devices similar to wireless routers on the projectors in front of some shops should be network set-top boxes or intelligent controllers.

6. If the requirements for image quality are not high, you can buy a projection of about 5,000 yuan, but if the requirements are high, it is recommended to buy a projection of about 20,000 yuan, and 1 10,000 yuan is a bit tasteless;

I hope it helps you. If you need anything, please ask me again!