Anyway, I'm glad that I have worried and tested him.
War for ages looking for an "IR extender" for Harman Kardon AVR645 my.
When he is now almost completely disappeared behind the screen it was high time!
A solution with the receiver and then an IR transmitter stick (or even danaben place) I did not want to, but directly behind plug a cable in the IR input of the AVR.
Works just fine, only the TX output (where actually the supplied IR transmitter are infected) is smaller than the input jack the AVR but that can be solved with a cheap jack adapter.
A good power supply is not present ...
... But there is so, which already for 5 euros ...
Better than 100EUR for Harman original part it anyway no longer exists ...
I am really very satisfied!
Was very happy because I now at last ever had a device that could be considered for my purpose.
But unfortunately it did not work reliably after a few days.
Whether a defect in the device I have not investigated further.
Went back, as I had in the meantime ordered this BTSKY Infrarotverlaengerung, which generally makes a better impression, incl. Power supply and still works and has worked very well from the beginning, yet a misfire (which in the reviewed here device occurred before until then no longer reliably went) ...