We don't see eye to eye, this kind of aesthetic first outlook is what the Beats franchise so big, and sorry if a smaller yet same sounding compressed format then it becomes pointless to keep lossless files especially when your library starts to get in the hundreds of thousands
Sorry, but as an engineer, I simply can not agree. mp3 is technically unsound. Yes, AAC is a lot better. And yes, being picky about the lettering when a component sounds awesome is eeeeeevil.
For your convenience, here is a mutitone spectrum analysis stereophile did some time ago (this does not endorse stereophile as a unbiased source of audio compenents reviews).
Keep in mind this is aworst case scenario with very complex music, a small Jazz combo can do with much less.
multitone flac:
320kbps cbr mp3 LAME
320kbps cbr aac
As we can see, the noise floor of the flac is as low as the component goes. And at around -135dbfs, we are far beyond the audible threshhold (conservative reserach shows around a cummulative -100dbfs noise to be unhearable). So that's a great start, as long as our amp also is nice and clean the only sound will be the sound of your headphone.
Now let's take a look at mp3. While the average is around -95dbfs which would be good enough, large parts go down to -90 and some down to -85. If you want to build a high end chain and listen to some metal, this simply does not cut it. So how does AAC fare?
Much, much better. The general baseline up to 16khz is easily transparent and no problem. The stuff from 18kHz - 20kHz looks a bit nasty but you'd have to have bat ears to hear that and even then, it's no worse than what mp3 looks across the whole spectrum.
In summary, FLAC is king, AAC is a very competent codec but mp3?? Hell no.
*)Disclaimer: technical baselines courtesy of NwAvGuy and his respective sources.
