I've been mixing mostly from headphones for practical reasons more than anything, but I will switch on my KRK's and tweak again. When listening through headphones I listen directly from my Presonus Audiobox. When I'm happier with my mix I will listen again but through my VRM Box which gives me room and speaker variations. Once I'm happy I then upload to SoundCloud and then listen through my Computer HiFi + sub. So I gues I don't need a sub but it would be nice icing on the cake when listening through my KRK's.