OK, I've thrown together a Rpi B+, the DAC+ which arrived today and it is all running. I've updated the kernel and applied the other modifications listed on this site. The good news is playback of CD quality (email@example.com) is working fine.
However, playback of HiRes for example 96kHz seems to playback at "twice the speed"....
Some testing with flacs reveals the following
16bit @ 44.1kHz fine
24bit @ 44.1kHz fine
24bit @ 48 kHz fine
24bit @ 96 kHz plays back very fast (volumio displays the correct information and generally seems to work ok)
24bit @ 88.2 as above
24bit @ 192kHz just sounds crazy
Many thanks for your anticipate help
RPi B+ DAC+ Volumio 1.41 & HiRes playback