I've seen many other sites have close options that questions belong on another site. E.g. English to Writers SE. I think Music SE should have an option "Belongs on Sound Design SE". I don't know if this type of thing is done on beta sites, but there are many questions that would be a better fit on Sound Design SE.
I don't believe it's done on Beta sites. The other thing needed is a high percentage of migrations go to the target (we have that) and a large number of migrations. Our question volume is so low at the moment that the number of migrations is also very low. That might change by the time we come out of Beta.