Something to note (not a problem): the B2 has quite a low "line out" signal. You will probably need to set the B2 volume high, around 60, thus at or near the max. Leave it there and use the Denon to control the volume you want to hear from the speakers.
If you did decide to use the B2 optical output to an external DAC (same socket, different type of cable), then the B2 output would be fixed and its volume control would have no effect. Again, not a problem, but useful to know.