i have this exact thing working using the following components
Amazon Alexa
AutoVera
Tasker
Hue Disco App
Imperihome
Sonos
Android Tablet
and this produces exactly as per this video with the exception i say Alexa Turn on Party Mode as “Party Mode” is the name of a virtual switch, tasker then does the rest
however is you used the following components for a purely Smarthings Solution this would work also
Amazon Alexa
SharpTools
Tasker
Hue Disco App
LANnouncer
Sonos (optional could plug amp into Tablet output instead)
Android Tablet (Preferably Wall Mounted)
then you could do the same easily