Its a Neutrik Speakon socket, its used primaraly for speaker connection but can also be used to carry power although I don think that would be the case in a house. Easy to get hold of the plugs,
http://uk.rs-online.com/web/c/conne...B20737065616B6F6E2673633D592677633D4E4F4E4526
Easy to wire up too...
Hopt this helps![]()