They don't get much attention these days, but last evening I listened some Gould (Mozart, hilarious lol!) and the magic is still there..
The thing is..the DT660 has such a different sound signature, it takes some time to get used to the Grado when switching..
I never liked the GS1k for orchestral though, so that hasn't changed. The Beyers do this very good in comparison..The amount of detail is almost the same as the Grado, the bass is more balanced though and
the mids are more there, which I like too.. The GS1000 still has magic with solo piano and string though.. but the Beyer is more balanced and unbelievable good for 130 euro..they do Jazz very well too!
Hope this all makes some sense..
Generally, I prefer my G-Cush'd 325i's (poor man's GS1K) but I do loves my 660 as well. I feel lucky to have both.