I just discovered that File Browser will connect to Volumio. Don’t know if this has been covered here. File Browser is a very cool app for iPad/Pod that will access your computer music files (including attached USB storage) and NAS devices, and play back almost any sort of file format. It has an icon in the play window, lower right corner, to connect to Airplay. I was trying it out an Volumio showed up! Plays perfectly.
…I guess it’s called Shairport, eh? Duh.