I saw a blurb (it must be several years ago) about using an Apple wireless device called Airport Express to play music files from my computer over a WiFi network on remote speakers. I bought an AE recently, plus a miniature amplifier from Amphony and some bookshelf speakers from Polk Audio through Newegg.
I was surprised, and quite disappointed, to find that in order to use this device in the normal way one must be a member of the "Apple club." That is to say, in order to send audio from my computer to Airport Express and have it come out through speakers, I need to have an Apple ID so that I can do "Home Sharing." I think this is outrageous. However, I do think it was pretty cool, in the end, to control this setup with my iPhone running an App called Remote.
I've never owned a non-Apple computer. That's a lot of boxes, starting from 1984. And I love OS X and its integration of the pretty Mac side with Unix underneath. However, it's clear that the future is iOS, i.e. not folks like me. So I was pleased to find, in a quick Google search, a somewhat dated article which explains how to stream audio in this way with Linux hardware.
About the amp, it is fun to produce music with so little hardware on site, but there is no ON/OFF switch for output, though there is a dial, which when dialed down still sends a nasty signal through the speakers when powering down. And I do like the sound a lot. Nice speakers!