Probably very sound advice.
My son followed up with this:
As far as interfaces with SPDIF inputs there isn’t much on the market that’s cheap. If he wants to get a more serious setup he could look into getting a Scarlett 2i2, which is a USB interface with two Mic Pre’s on it that double well as hi-z guitar inputs. It has two 1/4 inch outputs for speakers and a headphone jack. Not sure what he’s using the Central Station for currently but it doesn’t work out as an interface, it’s more of a monitor management system.