Signal to noise ratio ( SNR ), is a measurement that compares the level of the signal ( in our case of our audio systems, the music ) to the level of background noise, usually expressed in decibels. The lower the noise floor, the better ( ime ). As one gets " higher end " in this hobby, assumptions are made that noise is still present, even if hiss or hum are not audible. Information retrieval is always greater when the noise floor is lower. This measurement applies to many other areas, other than audio. I hope this helps. Enjoy ! MrD.