OK, I'll talk about Grado mods for a moment. I'm using the Bilavdieo "Specials" (SR225 Woodies) tonight. Earlier, I brought down my night-time, going-to-sleep headphones - the Sennheiser HD555s. These have had the mod performed by removing the foamy rectangles from the screens of the shells. I thought the Sennheisers sounded OK with my portable players - especially, when winding down to get sleepy and drift off into snooze-land.
How was the experience of using the HD555s down here on the main level? Not too pleasant. The music just didn't sound accurate to me. The bass was a bit bloated - not "fast" like it sounds with the Grados. After switching back and forth for a few songs, the Grados were plugged back in and now I'm enjoying them again with my music. In all these years of my "music nirvana", which has meant trying to achieve that perfect sound that would fully engage me in the music I'm listening to has been hard to achieve. Very hard, actually. Quite expensive, too - when you look at all the gear I've purchased and sold over the years.
Well, I'm happy to report that these Grados have helped me reach that "nirvana" - I realize some people don't like the level of detail that they provide. However, when modified, these things will perform miracles for your listening experience.