Hey Guys. . . I think it is difficult to tell for someone listening through home speakers or car stereos. . . or even a pair of very good consumer grade headphones. But as a DJ. . . the difference is astronomical when you play it in a venue through a loud system. The difference is even more astonishing when you play through a system that is EQ’ed properly and has speakers and acoustics with a wide range of frequency responses.
I’ve made the mistake of playing a set with a couple of MP3s mixed into a whole bunch of WAVs and the owner of the bar (not knowing anything about sound) ran over to the booth and asked “What’s wrong with the music suddenly? It sounds like [low quality].” He didn’t know I was suddenly playing an MP3 track. . . he just thought something broke.
Also. . . in my experience the diff is more obvious in tracks that has more electronic parts, or even classical music. . . where the instruments are of a bigger range and are more distinguishable. I’ve heard parts in a WAV that I’ve never heard in an MP3!!????? Serious. . . no joke.
Lastly. . . how the track was recorded and mixed matters too. . . I mean. You really can’t tell much if a track was recorded live in a room. . . etc etc.