Is it safe to splice an output extension onto an AC Power Adapter?
Obviously if it looks like a bigger version of the Mini-DIN, it must be a DIN connector.

The original DIN standards for these connectors are no longer in print and have been replaced with the equivalent international standard IEC 60130-9.
While DIN connectors appear superficially similar to the newer professional XLR connectors, they are not compatible

Alternatively, it could be a &quot;power DIN&quot; connector, which isn't a DIN standard at all. Also known as a 4 pin power connector (Mouser Link)

A male 4-pin &quot;Kycon&quot; power connector, which appears similar to a Mini-DIN connector


As for cutting and splicing the connector, yes, that's possible, and can be done safely. Just make sure your extension is of a similar gauge wire for the voltage and current that it will carry. Standard cable splicing technique should be followed, nothing special about it.