OT: ogg file blind, listening test

[jeffslists]

Since someone here has just mentioned .ogg files I was wondering what 
encoding rate I need to use so that I cannot distinguish my .ogg file 
from my cd.  A couple years back I read about a double-blind (maybe just 
single blind) study with 256kbit constant bitrate mp3's.  The listeners, 
who were described to have excellent ears, could not distinguish the 
mp3's from the cd's, though a computer could.  I don't care what a 
computer can distinguish.

I have searched the net several times and found no similar study with 
.ogg files.  Aren't there any people who have done a blind study with 
.ogg files?  I want to know the minimum quality settings I can use with 
.ogg in order to save hd space.  I have about 120gb 256kb mp3 music.  
According to my preliminary research I think I can save at least 30% space.

Thanks,
Jeff