Hmm, interesting. I actually think putting anything in front of my t20v1 does more bad than good, even simple earpads that are lined with "acoustically neutral" cloth just ruin the highs for me. Strange though, I have more of a problem with the low mids than any of the treble. I'd guess it's around 2-5k that seems bloated to me. I'd have to do a sine sweep to check.