Man, I really wish I had not come across this post!
Lots of reviewers (certainly not all) note that grado's are or at least can be, fatiguing for lots of listening sessions due to a treble emphasis.
Yet, your experience is quite different. Are you listening at lower volumes? Do you listen to a lot of music with less treble emphasis?
i think it can depend on what one's ears are accustomed too. up until i tried the sr60i, the best headphone , the most "expensive" the the senn hd203( $30ish), and the AT ad300( which was bought as a discontinued model) at $46 . i really liked the ad300, but it had a rattle somewhere in the housing, so it went back to amazon, and i tried the sr60.
with my home systems of the past , i generally liked, preferred a warm, lush, tube sound, exept for linn, and naim products, which are generally regarded to do the rhythm, and pace thing. something that lends itself to "musicality" .
I've heard 50- 100k systems that hurt my ears , a certain huge wilson speaker, mark levinson system pops to mind, for all the things that system did right, its brightness was awful to me.
i too was worried about the grado's "bright" reputation, but i kept hearing about its rhythem, pace, musicality i just bought from a place i could return it if i didn't like it.
well i did return it, and got the 225, and i have an alessandro ms1 on the way, due to its possibly being a little warmer.
it'll have to be damn good to make me return the 225's !! hell, i may keep both, and get a better dac, or amp, i bet the grado/alessandro's love tubes !!
i may have other headphones here and there, but i suspect i'll always have a grado from now on !!