CoreAudio should be all the devices labeled as CoreAudio, I suppose. But I think the post I linked to may be inapplicable or old or something. Sorry, not a big direct output guy myself, I relied on @mjw who is nearly always right 
I checked now on my Mac and my device, just the MacBook Air Speakers, is labelled CoreAudio, too.
But when I play to it, it also shows OS Mixer in the Signal Path. However, it does play fine at 96 kHz, which is the maximum (default value) configured in the Device Setup for this device:
However, the same works when I enable the System Output and play through that instead - no difference between the CoreAudio and the System output:
Maybe check your device setup and try your MacBook Speakers device, too. The sample rate is under advanced:
As for the Bose, check the device setup there, too, I guess. But are you sure that the Bose device accepts higher than 48?