great idea for a thread, this is something i've been "investigating" lately as well. i did not read any posts in the thread or read the poll results before listening. i loaded them into foobar and used replaygain - i was quite certain which file was lossless and upon reading around the thread it seems i was right. as others have said i immediately picked up on the "swishiness" of the lossy file. but this is the sort of thing that's a lot more obvious when you are able to compare them side by side. in any other context it would be indistinguishable, i think.
what is more interesting to me is taking the best recordings i can think of, applying replaygain, and comparing them. i have recently been doing this with some of my Steely Dan tracks and i have to say that i cannot tell a difference, even with my headphones, let alone my nearfield monitors. i've been listening to various 24/96 FLAC files from Gaucho and comparing them to some 192kbps mp3s i also have in my library; after replaygain i cannot really discern any difference (using foobar's ABX plugin). this was surprising to me as i had previously (a few months ago) believed that i could tell the two apart. i always believed the difference was minor: the way the track was recorded/produced/mastered initially is of much greater importance than the file you ultimately listen to on your computer.
Edited by TheAnomaly - 5/18/13 at 9:47pm