Hi jost.alex,

the part number for the mains adapter (AC-P5005F) is: 988521596.

Sony Europe

I bought the same device. It came with the SONY AC Adaptor AC-P6005F power supply unit, but 6V.
Input: AC 100-240V - 50Hz, 6W
Output: DC6V, 0.5A
The original power supply is recommended for Sony. If I'm not mistaken, the polarity on the DC side is reversed. The positive pole is inside the plug tube, the negative pole outside.
With most power supply units it is the other way round.
The Sony plugs have a small yellow ring on the DC plug for identification.

I bought the Sony device from the Digitec shop almost 3 years ago. A power supply unit was included. A quick check of other suppliers shows that, depending on the sender, a power supply unit may or may not be included.
I would like to upload a photo of the power supply unit, but I can't.
Hence the technical specifications: Sony Adaptor P5005F 5 V, Input 100-240V, 50/60Hz, 6 W, Output 5V .5A 2.5 W