Hi
Regarding this bit of your question "
would I also need to add an external amp as well"
The B2's optical output is digital the and what the Digital to Analog Converter (DAC) does is to convert this digital data stream (1's and 0's) into an analog waveform.
The DAC itself is not an amplifier and the analog output from a DAC would need to be amplified to drive a speaker. However some DAC units do have a built in headphone amplifier (and or a Bluetooth transmitter).
The answer to your question is therefore "yes".
Fred