I have this surround sound system at home that is very old and have these strange sound input sockets that I have never seen before. Does anyone know what kind of input socket this is?
They appear to be the 220V inputs (source feeds - Fuente alimentación) for each device; (L and R) as each input looks like it has two connection points. It has a custom connector that I cannot identify. If you can read spanish the manual more information is here: www.kroser-electronica.com/descargas/catalogo2007.pdf
Looks like the 2-pin DIN connector like others said, and you can insert it with the small pin to the right or left. Or is some custom connector, to find out for sure you would have to open the panel up to look at the pins.
I also found the same hotel sound control thing on another website where someone is looking for a technician to fix it. And his version got 5-pin DIN connectors link: Other website with 5-pin version
Some more info and pinout of DIN connectors: Here
The fastest way to find out what sockets they are, is to open it up and look how many connectors come out from the socket.
I hope this helps.
Wikipedia specifically mentions a version of the two pin female din where "Most common is a three-hole female connector with one circular hole on either side of the spade hole, one of them with an aux contact and one without, which provides the option to leave the internal speaker connected by inserting the plug twisted by 180°"
I can't find that specific looking DIN anywhere though.