I think there's a graph I can plot showing the correlation between post count and the propensity to say yes 
Anyways, I don't think I'd be able to tell, but I've never tried ABXing at 320kbps. I've only gone up to around 200-250 (vbr), and I could tell an incredibly slight difference but didn't really care. This was all with modern Lame versions. Ogg Vorbis and AAC/M4A encoders both perform a bit better than Lame. In full disclosure, I didn't have quite as good of equipment as I do now, back when I did said test.
Edited by soundstige - 1/28/12 at 10:01am