I love IEMs , They are almost my favourite type of phone, isolation, light weight, and an intimate sound.
I don't fuss over db , but keep the levels at my own volume 'sweetspot' above or below this I don't enjoy the sound as much.
Recordings and music tend to have their own 'sweetspots' but these have to fall into my own.
If that makes any sense!
But then I am not an endurance listener , I am amazed at the hours some people listen for!
I guess it depends on personal...