IndustryStandard
I found out last year that the regularly streamed 256 AAC actually sounds slightly better in the mids and highs than 320kbps MP3 and the AAC format was developed by the same guys who made MP3.
It turns out that it’s not all about the number. I feel really sorry for Beatport Link who actually send out high quality streamed sounds and people are always grilling them for being 256.
There are countless articles about it, I just googled this one and to quote it:
“A rule of thumb is to use 320kbps MP3s and 256 AACs for professional use (highest bitrates). Or use the original WAV/AIFF uncompressed files.”
As for the lossless files, I genuinely can hear a slight difference in WAV/FLAC on a good sound system.
To me though, everyone has fun, loves the music, and it sounds great, when on a dance floor listening to a DJ playing MP3/AAC. That extra 2% shine doesn’t seem worth the storage costs at all. You can become very efficient with MP3/AAC files.
I do admire when someone has actually pulled that off and has thousands of tracks on those formats, mind.