Home sharing in the Music app only works when the music is stored on a Mac / PC.
You could try downloading VLC on your iDevice, point it to your SMB share on the Time Capsule then tell it to stream to your bluetooth device.
It's well clunky compared to the Mu-so, I've got one and love it.
BTW the Mu-so works best when streaming from a NAS running DNLA/UPNP, I've got a Synology.