Hmm... I use headphones when I make my music, because I think music is best heard that way. It gives a much wider sound, and it's easier to hear small details (and the neighbors don't get disturbed, lol). But today when I played my music through the speakers for some RL people that hadn't heard it before, it sounded much worse. And I don't know... do more people listen through speakers, than through headphones? Maybe my songs would get higher score if I optimized them for speakers. I really don't know. HMMMM...
EDIT: OK, after some communication I've come to the ultimate conclusion: Headphones is always better. :)