Does using a powered subwoofer make better sound?

The quality of the subwoofer must match your other speakers.Subs are good with a small speakers. The sub will make a small speaker sound more like a fullrange loudspeaker. Will the match be seemless? No it won't, but with careful set up you can get it close. The biggest mistake people make is having the sub to loud. You should only hear the bass intergrated into the music. You should have no sense of the sub being there. If you are using a sub for movies you would have it set louder. Movie dynamics are extreme.