Otherwise... how would we all be able to use modular synths if nobody can listen to it because a DC signal might destroy our speakers... it's somehow a bit confusing to me to be honest...
-- GarfieldModular

As Lugia said, using a transformer coupled output module is a safe and professional way to avoid DC problems in studios and going into a P.A. system (if a bit costly). In real life all mixers I have used, even cheap ones, remove DC from their outputs. If things sound gnarly out of your speakers when they shouldn't you probably have DC in your signal going into the mixer (or other monitoring device). A scope will help you see that.