SOLVED! At least for my 2015 iMac and MB with external speakers, which should
be the same as plugging in any external device, like a monitor, with speakers. I tried every fix on this
forum. Nada. Then by chance I switched the input in Sound preferences
from Boom2Device to Internal Microphone. Tada! Don't ask me why that worked, but Boom2 is back in
business creating beautiful music. Now if we could just get multiple speaker profiles, hotkeys for select EQ settings, and discrete device settings, all will be well in paradise (mostly).
Could you please let us know whether "Boom Helper" option is checked under Boom 2 Preferences?
If not, please check the same option and see if it helps.