HIFI Planning - Which Control and Various Questions

How can I tell if the receiver can do that? Example YAMAHA RX-V77, on the website it only says "Output via Zone B provides 2-channel sound in a second room; Zone B output means that the user can also listen in 2 channels in a second room while 5-channel playback runs in the main zone (same source in both zones)."

The description of the receiver states whether it is a 7-channel or "only" 5-channel receiver (which one exactly from Yamaha do you mean?). According to your quote from the manufacturer, it is a 7-channel receiver.

..and then I can use Front R+L for Zone 2?

I don’t understand the question! You have five channels in the living room, i.e. 5x receiver to speakers. How you connect the speakers, whether with plugs or like I do by running the cable directly, does not matter. Of course, you can also simply lay the speaker cable on the floor if it doesn’t bother you or is not visible.
Then you still have to run two more lines for the second zone in the dining area. Here, too, you can work with plugs or simply pull one long cable through.

Thanks for the picture. What are such sockets called?

Good question, it’s from the Gira switch program. It is a concealed outlet facing downwards, where you could also, for example, use sockets for LAN. Unfortunately, I don’t have an exact article number from the electrician.

It is stated in the description of the receivers whether it is a 7-channel or "only" 5-channel receiver (which one exactly do you mean from Yamaha?). According to your quote from the manufacturer, it is a 7-channel receiver.

For example, YAMAHA RX-V771 ("Powerful 7-channel surround sound with 160 W/channel (4 ohms, 1 kHz, 0.9% THD)" - 7 channels automatically means that I can operate 5.1 + 2.0 without a second amplifier?

I don't understand the question! You have five channels in the living room, i.e. 5x receiver to speakers. How you connect the speakers, whether with plugs or as I do by pulling the cable directly through, does not matter. Of course, you can also just lay the speaker cable on the floor if it doesn’t bother you or isn’t visible. Then you still have to lay two more lines for the second zone in the dining area. Here you can also work with plugs or simply pull a long cable through.

In the LYNDAHL LKL005 I have according to the picture 2x6 connections so that I can connect 5.1 speakers. I now had the following idea: Receiver -> Sub & Front R+L & Center directly via speaker cable -> Rear R+L: from receiver > LYNDAHL > flush-mounted duct > output > speaker -> Zone B: same as Rear R+L

There remain 4 inputs unused.

For example, YAMAHA RX-V771 ("Powerful 7-channel surround sound with 160 W/channel (4 Ohm, 1 kHz, 0.9% THD)") - 7 channels automatically means that I can operate 5.1 + 2.0 without a second amplifier?

Yes, as long as a second zone is provided on the receiver.

According to the picture, the LYNDAHL LKL005 has 2x6 connectors so that I can connect 5.1 speakers.
I had the following idea:
Receiver
-> Sub & Front R+L & Center connected directly via speaker cable
-> Rear R+L: from receiver > LYNDAHL > flush-mounted conduit > output > speaker
-> Zone B: same as Rear R+L

Yes, that can work.

This is what "cheap" boxes look like if you don't want to work with plugs.

And these also require less depth than boxes with sockets for banana plugs. I personally have always chosen the terminal version for speakers, without plugs/sockets. Cut-cut, the cables are the right length and still connected quickly.

Goodbye, hi-fi enjoyment - clamping options? Best with 0.5 gauge cable

I believe the ohmic resistance is, if anything, lower than with a connector, because in both the plug and the socket the cables are just clamped, so there is one more connection in total! Funny that you know my cable thickness. Just because I use something different, you don't have to start a personal attack. I certainly don't send 100W at low voltage through cables that are too thin. But there are people who still hear an improvement with gold-plated digital cables(!).