I’ve been using Airfoil by Rogue Amoeba for years to pump audio from my Mac to my Airport Express… but I hadn’t realised they’d created a FREE app named Airfoil Speakers, that turns your iPhone/iPod/iPad or any Mac or PC on your WIFI network into a wireless audio receiver.
That’s saved me buying another airport express for my BBQ’s during the sumer, just plug my old iPod touch into the amp in my garden, switch on Wifi and I have streaming audio in sync throughout the house and garden!
So I won’t retire my old iPod Touch to a video wall just yet