This app was mentioned in 2 comments, with an average of 1.00 upvote
Thanks, it is actually quite a nice app. I've been using Squeezer https://play.google.com/store/apps/details?id=uk.org.ngo.squeezer
It sounds like you are asking what the benefit is of one vs another, but it is possible to use them together. I hope I understand your question properly. If so, here is an option that includes your Squeezebox vs Chromecast that is pretty inexpensive. It's a little janky, but it works.
Step 1: Logitech Media Server (Squeezebox) running on a computer that allows access your mp3s, Pandora, Spotify etc.
Step 2: Install Chromecast Bridge plugin into Logitech Media Server (LMS) http://forums.slimdevices.com/showthread.php?104614-Announce-CastBridge-integrate-Chromecast-players-with-LMS-(squeeze2cast)
Step 3: Plug a Chromecast Audio into whatever music device you want to stream music to.
Step 4: Install Squeezer App (or something similar) to an Android device ( https://play.google.com/store/apps/details?id=uk.org.ngo.squeezer )
Step 5: Stream your audio from the Squeezer app to one Chromecast Audio or sync them all up.
Optional Step 6: Install Squeezeplayer directly to Android phone/tablet to stream your LMS audio to the device ( https://play.google.com/store/apps/details?id=de.bluegaspode.squeezeplayer )