I get lots f ambeint noise while recording, but the S:N ratio is high when an instrument is being played or vocals being vocalized. Just clip out all the silence between vocal phrases. It takes abit of time, but you get rid of all that unwanted noise. Also saves hardrive space. If you only really sing for 1 1/2 mins in a 4 minute song, why on earth keep the other 2 1/2 mins of "space" in the recording at all? Cut it out.