closed as off-topic by DoxyLover, Bence Kaulics, Warren Hill, RoyC, Lior Bilia Dec 14 '18 at 2:07
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – DoxyLover, Bence Kaulics, Warren Hill, RoyC, Lior Bilia
I'm reasonably certain you need an IEC 60320 C9 plug to mate with that connector.
Wikipedia has this to say: "This kind of coupler is used by Roland Corporation for a couple of synthesizer and drum computer models (for example: TR-909) and by Revox for many older models of their HiFi equipment (for example, A76, A77, A78, B77, B225). Was also used heavily on Marantz Hifi equipment in the 1980s and 1990s." (source)