I've done a side-by-side comparison of the same song mastered to what amounts to CD level, then to Spotify level, then Apple Music level. Then set each appropriately to the same volume level.

Its not hard to do, but it is very ear opening to hear the difference. They all end up sounding the same "loud" and nothing changes in terms of "heft". What does change is the spacial impact. Songs mastered to say -9 LUFS, which about as loud as you can get things in the digital realm (maybe -8), end up sounding less spacial when played at -14 LUFS or -16 LUFS.

I found that songs that were mastered to the level its to be listened to as a max ended up sounding much better from a spacial aspect. And when turned up further with a volume knob, they have more impact.

Also, when a song mastered to that volume (-9) can also have more revealing issues at lower volumes. The latest best example is Ed Sheerans Divide. Several of those songs are actually distorted due to loud mastering and I found that I disliked listening to them despite how good the songs are.

As I've been working on getting Apple certified for the Mastered For iTunes program. I've found that Mastering to -16 LUFS with well mixed material has actually made it easier to run things thru their applications and avoiding volume based distortions. Which is an improvement on the loudness wars.

p.s. I use the iZotope Insight, it has a plethora of information that it tracks.

Jody Whitesides
A Funky Audio Lap Dance For Your Ears!