Anyone who doesn't do ABX testing everything is very likely wrong and subject to bias... lolr
Maybe people have better things to do than set up ABX tests over an utterly redundant issue. mp3 has audible differences which can be proven with a null test - but honestly I cant say that the differences are DBT-proof, at least not with my gear.
If you really feel like wasting time though you can create your own test or run with the files
from here
I tried this with a 24/96 WAVE to 320mp3 and even then the difference is very small, and my gear is not very bright (no pun intended) so I don't like my DBT chances.
Does this mean I go and rip my whole music collection to mp3 - erm no! I want to keep a bit perfect copy of my audio.
You can feel free to save yourself $90 on a hard drive and rip everything to mp3 - you probably won't hear the difference unless your gear is very bright/revealing.
But unfortunately that doesn't do it for me - I want to wring out every last microscopic theoretical drop of SQ possible from my music - especially for archiving in case I get higher resolution gear down the line.
In the meantime I have better things to do with my time than worry about disk space lol!