I listen to Sirius/XM satellite radio (in my home office), Spotify Premium, or occasionally songs in my iTunes library.
The biggest issue I run into is that my home office and kitchen are close enough that I frequently walk back and forth while doing things, and also can hear the other location in the background, so the audio being in sync is an issue. Fortunately, this was surprisingly easy to solve.
One part is the Airfoil software from Rogue Amoeba software. It runs on a desktop or laptop Mac or Windows PC.
I have the satellite radio connected to the audio line input on my Mac. Airfoil can also capture the audio from Spotify, iTunes, Pandora, etc. as well.
On the output side I have a couple options. I have an Apple Airport Express in the kitchen that provides Wi-Fi coverage and also conveniently provides an audio output. I just connected the Airport and the Logitech speakers with a 3.5mm stereo audio cable and that was it! Done!
The Logitech speakers have built-in rechargeable batteries and an Apple 30-pin connector. If I want to listen to music somewhere else, say outside, I can just pop in my iPhone 4 and run Airfoil Speakers Touch from Rogue Amoeba on my iPhone, and stream to that over Wi-Fi. Neat!
I also have Apple TVs in a few locations, and I can stream audio to those.
The nice thing about the Apple Airport Express, Apple TV and Airfoil Speakers is that they're smart enough to stay in sync with each other. I mean really in sync - you can stand in the middle between three different output devices and they match perfectly whether on Ethernet or Wi-Fi. They are delayed a second or two from the source, however.
What about at my desk? Airfoil handles that, too. If you select Computer, it will output audio synchronized to all of the other outputs. And, if the source is an application (like Spotify), it can intercept the output and only play the delayed, synchronized output through your computer speakers. At least it can on the Mac. That is very cool!
And if you use Airfoil to stream Spotify to an Apple TV, the track info and cover art appears on the TV. That was rather unexpected.
Now that I figured out how easy it is I want to put inexpensive but reasonably good sounding computer speaker/subwoofer systems plugged into Airport Expresses all over the place!