I saw this survey, and did it, but coud not wait for the results !
If I were to be the winner, there would be an Amperior to sale at a special Head Fi price ;-)
Unfortunately, I won't be able to compare the Amperior with the HD-25 that I never heard !
The isolation is good (certainly not a dealbreaker as far as I'm concerned), just a bit less than the Westone 2 IEMs, something that I expected indeed
I guess it is similar to HD-25 with velours pad, so...