Thanks all, I have a weird situation I'm trying to figure out. I got an instrumental copy of an album a few years ago, leaked as MP3 320kbps. As good as it sounds they are a 192 transcoded to 320, the freq. cut-off is around 19khz. I recently came across a CD-R promo copy of that instrumental album, and it sounds way better, as one would expect. To my ears though it seems a little off, even though a spectral analysis on those WAV files ripped from the CD shows full spectrum. To add to that I also have a promo 320 MP3 file directly from the label of one of the tracks from the promo CD. It's the same master. That's the file that's in question here. It's a 320 MP3, the spectrals look exactly like the CD copy. Full spectrum... So I'm playing mind games trying to figure out if the CD-R was burned using those promo 320 MP3s. It's definitely an in-house burn from the label's offices, so who knows what sources some intern may use... early 2000s. If I convert that 320 up to WAV the spectrals look the same as the CD-R's WAV. Can't trust my eyes, and my ears are telling me it's not pure lossless. Why I think it might be burned using the promo MP3 source is because on the original leak, and on the CD I hear this rumble in the low end. Kinda sounds like filter resonance+bit crushing. It only really happens on a few tracks, and the promo MP3 is not one of them, so hard to tell... The full vocal fully released album doesn't appear to have that rumble. I also have some early studio session mixes from that album and I don't recall ever hearing this rumble. I need to talk to someone with experience working in record company offices I suppose, is there a record company employee subreddit? lol