[EYEdROP]

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. 

 

[BustyBloke]

I have often wondered if noise isolation + active cancellation can "stack" on top of each other.
 
I used to wear my Shure SE535 under my old Phitek Blackbox M14 NC headphones. I did find that this combo reduced noise very well, but in the end I found it too bothersome to carry the Blackbox around with me all the time. It was a pain to remove two sets of headphones every time I wanted to talk to someone. On top of that, I now live in Hong Kong and the heat during summer makes wearing full sized 'phones very uncomfortable.
 
The Blackbox is from a New Zealand company and I don't think they are particularly well known outside of Australasia. Their specs claim up to 92% (whatever that means) or 22dB active noise cancellation plus 35dB passive sound isolation. Here is a link to their new flagship product: http://www.blackboxonline.com/store/us-products/m16-us/
 
I don't have customs, but I suppose the next best thing in terms of noise isolation would be the Etymotic ER4's, which boast 40 odd dB of isolation with foam tips. If I pair my ER4's (at brain-violation-level deep insertion) with NC headphones, would I be effectively getting 100dB noise isolation? I'd imagine that at some point that bone conduction from the rest of your body will still transmit noise and vibrations to your eardrums, no matter how much stuff you jam into or put over your ears.
 

 

[EYEdROP]

According to some sources online, 70db of isolation is sufficient for a decently high dollar studio control room. I was only isolated about 60db if you count the isolation the walls provide.
 
For me, Im thinking a high end pair of customs plus some extreme isolation muffs could potentially give IEMs a SQ advantage over full size cans, or at least a run for the money. IEMs and full-size are still apples and oranges. But they taste great when mixed together.

 

[jjmai]

I was thinking about doing this as well while on the airplane.
Anyone know a good comfortable active noise-cancelling fullsize headphone, with large and deep ear pads?