The project had 3 clear goals:
1. Remove the disastrous cable mess around the Hifi-system and TV
2. Avoid repeatedly creeping into dark corners to reconnect the cables (always increasing the mess mentioned in 1)
3. Do 1 and 2 without decreasing functionality of the whole system
After considering all necessary signal-paths, it turned out, that one component was missing: An analog 5.1 switch. My 5.1 receiver (from Yamaha) is almost 10 years old now, but it still works perfectly. Unfortunately, it has only one 5.1 input (and lots of stereo inputs). Now, I have 2 sources of 5.1 audio: The DVD player and the Media PC.
And to make things worse: Many stereo movies on the PC (e.g. rips from VHS tapes) are encoded with the old Dolby Surround method. The Yamaha receiver handles them perfectly, but only when the signal comes into a stereo input. This means that the stereo channels form the 5.1 signal must also be routed to a stereo input of the receiver.
So I was searching for something, which does the same as the green box in the following figure (the AUX channel is reserved for future extensions):
Googling around revealed only one solution, which is unacceptable because it only switches between 2 sources, needs a power supply (violating goal 1) and costs € 258. All other search results were people saying that this sucks.
The question was, if some other device can be tricked into doing exactly what I want, and the answer was yes. The idea is to (ab)use the video wires of scart-cables for the additional audio channels. So I got 3 adapters with one scart connector and 6 cinch connectors each:
And a scart switch-box:
The funny thing about the switch box is, that the stereo channels are available at additional cinch connectors (right side), so I can route front L/R to a stereo input of my receiver, like I wanted.