How many wires for PS-ON and an XBOX 360 PSU?

This is a very simple question (I hope): I am wiring up a socket so that I can power my delta printer with an XBox 360 203W PSU. All is going splendidly so far - I can turn the PSU on and off by connecting the 5v and sense wires in the PSU socket.

Now I am planning to use PS-ON as a way of controlling the PSU, leaving me with the option of turning it on with a switch or via the software. I know about removing D1 so that the Arduino is powered from USB, and about the fact that I'll have to set the correct PS-ON parameter in the Marlin firmware. My question is, do I run just 1 wire from the XBox "sense" terminal to PS-ON, relying on the main power -ve connection to provide the return path, or do I have to run 2 wires, i.e. to the XBox socket's "sense" and 5v terminals?

Thanks in advance,
David

Edited 1 time(s). Last edit at 04/06/2015 11:44AM by David J.

Just one wire should enough, the main ground connection also serves as ground for PS_ON.

Thanks - that's what I suspected. I'll try that first, and get inventive if it doesn't behave as expected.

In conclusion - 1 wire was enough!