You could use an Airport Express with a mini-optical digital cable feeding a conventional DAC (no need for USB). I run this way into three audio systems in my home. Nice, cheap, simple and I'm able to control it all from my iPhone.
I don't stream wirelessly to the Airport because I have a wired network which is nice because interference/dropouts are never a problem. You mentioned network cabling, so this might be perfect for you.
I don't stream wirelessly to the Airport because I have a wired network which is nice because interference/dropouts are never a problem. You mentioned network cabling, so this might be perfect for you.