Folks,

Debate rages in both audiophile and professional audio circles about the importance of low-level artifacts such as distortion, jitter, quantization noise, and summing errors in DAW software. This article addresses the audibility of very soft artifacts, and includes Wave files you can download to discover for yourself at what volume level these artifacts can be heard.

http://www.ethanwiner.com/audibility.html

--Ethan