Insecure about some reviews very cheaper remote extensions, I looked but then again the slightly higher priced Marmitek product range. And I finally found exactly what I was looking for. Where the competition with individual small "eye" works that one must stick to each device to be controlled (because if one knows exactly where the IR receiving point is located), there are of Marmitek the "Control 6 XTRA IR Blaster" unit where you only need a "transmitter" per cupboard. This channel then passes the signal to all devices in the tray.
Well - and it works. At First Attempt. The installation took 10 minutes, a short test run, everything Paletti - and the individual components were glued clean using the enclosed pads. The receiver is below a Canton-Soundbar and is completely invisible.
Are driven by me an Apple TV and a Panasonic Blu-ray player of the latest design. The second transmitter I have not needed. Maybe later - who knows what is to come.