Here's what I"m seeing:
this screenshot shows that my AE isn't seeing any of the 5 GHz FiOS networks, while
this one shows that it
is seeing other 5 GHz networks at the same time.
I am
too. I assume you scrolled down the list of networks to see if the 5 GHz bands showed up later further down the list.
I suspect that playing music to an AirPort Express is an exercise similar to the one in which I"m engaged.
To run AirPlay on a Mac, your stereo must be plugged into your AE and
you must be able to connect to its network.
"
you must be able to connect to its network" may not be not the best wording. Airplay works fine from my Mac, my iPad, iPhone, and Apple TV to a sound system connected to an AE that has
joined the network created by my Netgear WiFi Router. Perhaps a better wording might be
you must be connected to the same network?