Identification of power connector
This looks like a 4-pin mini-DIN connector.

Electrically, the connector itself is usually the least sensitive part of a supply. However, mini-DIN is designed to save space, so you can easily run into its limits.

The actual specs depend on the model; you always have to the check the datasheet.
(For example, the CUI MD-40 is rated for 1 A at 100 V, or 2 A at 12 V.)