I just set up my garage stereo this summer, and I'm happy with the result.
Inside my house, I've changed over to playing music with a dedicated music server (running Vortexbox) using a Logitech Squeezebox Touch player to feed my receiver & speakers. All of my CDs are now on the server, without any loss of quality, as I'm using .flac files instead of .mp3 (these really do sound as good as the original CD.) I've got a lot of vinyl too, which can't be beat as long as you get the turntable sorted out.
For the garage, the criteria were to keep it simple, safe, out of the way, and be able to play from the server in the house, all without much expense.
Wireless is strong in my garage, but I still ran Cat6 cable. It's a 100' from my living room server to the common wall inside the garage, and a Cat6 run was simple going thru my basement.
The Squeezebox Touch players were discontinued this year, so for the garage I built a "VAMP" player from a $29 Pogoplug. The Vortexbox forum shows plans on how to do this, and you get a player with USB out that then needs a convertor before connecting to the receiver. I like the Panasonic digital receivers and they don't need an external DAC, so from the Pogoplug VAMP player, a $30 USB to SPDIF convertor outputs to the receiver.
Control is wireless back to the server, using Ipeng app on any apple device (Ipod, phone, etc..) or any computer via the web interface for Logitech Media Server. The receiver and player are powered on by a single wall switch. Sounds much more complicated than it is, it all just simply works, and lets me play any music I own, or stream any internet radio. I just flip one wall switch to power it all on, then use the phone or Ipod as a remote control. Never have to touch anything on the shelf or anywhere else, as the server in the house is a low power intel atom device that stays on 24/7.
First pic shows Pogoplug base VAMP player on left, the Panasonic rcv'r, and the small silver box on right is the USB to SPDIF convertor. I put these on a shelf high enough to clear the tops of 6' storage cabinets on casters that can move underneath.
Speakers and the system described above are set against the garage's common wall to the house, with speakers facing across the garage (it's a large-ish garage that's wider than it is deep.) To keep the speakers up and out of the way, I used punched angle stock held up with threaded rod and beam clamps. This way the parts are adjustable to fit different size speakers, or change the angle they project (mine are tilted down & toed in slightly) To "fly" speakers safely, don't trust screwing fasteners direct into the cabinets, take the time to suspend them securely. I rigged mine up in a hurry, but it seems to work well and they are held safely. Speakers are Paradigm 5se, these sound good & have rubber surrounds instead of foam. That rubber won't deteriorate like the foam ones, for use in the garage (not climate controlled) it's probably longer lived.
John A