I've just installed the A-Control Software, and I would like to change my speakers' IP address. I'm using an Avid Artist Mix, and I need it to have a static IP address to work properly.

It depends on whether you use a DHCP server or not.

With DHCP server: Set a static IP in the DHCP server and you're done.
Without DHCP server: The Zeroconf IP address is always static. You do not have to do anything else.