I automatically think of it as a girl name. I think it seems too feminine for a boy. Doesn't matter how many Ns. Sorry - I know how annoying that is, because I want to scream NO when people say they like
Rowan for a girl. But the only
Quinn I know is a little girl.
I do think that a
Quentin,
Tarquin, or
Quinton could be called
Quin familiarly, if it happened that he was a guy who could carry it off without it seeming feminine. And most guys likely could.