Today I wore my Ultimate Ears 200vi underneath my beyer DT48 sealed cans at 3AM this morning. The idea was to have as much isolation and the lowest noise floor possible. With the music off, I could hear my heart beat and my breathing, as well as creepy little sounds that I think are in my head. It was eerie and artificially quiet. The IEMs were pressing hard against my ears and was very uncomfortable. But it made for a great seal.
I turned on the music and was in heaven. Even with a cheap set of $40 IEMs, the sound was amazing for what it was. The low level detail, soundstage, and decay were much improved.
Soft sounds can still be heard even though louder sounds are in the music. This is especially true during quieter parts of the track. I think the lower noise floor really helped unlock the potential of the IEMs because it extends the limit of the softest sounds that the headphones can reproduce. Thats why the decay sounds so much better.
I think the optimal would be something like those gunshot ear protection headphones or drummer headphones with a pair of customs underneath. That would provide some extreme isolation. I don't have customs or earmuffs so someone should try this with their QC15 and JH-13s and report their findings.
BTW, after midnight is a great time to do this, with as many electronics in your house turned off as you can.
Edited by EYEdROP - 1/27/12 at 10:28am