Thanks for the suggestions.
Yes, I am using a headphone amp (Bellari HA540).
I know the DT-770 is the obvious choice, since I enjoy my DT-880's, but I was thinking it would be more fun to try another "flavor" in the new pair. (Maybe a bit more bass would be nice.) Don't want to mod my DT880 as I will still use them when open cans are not a problem, or if I feel they better suit the music I want to hear at the moment.
In searching the boards,
The Denon 2000 has a lot of fans here, but many note the isolation is not that great.
The ATH-A900 does not seem to muster much passionate support. Maybe the 900X will fare better.
The Shure SRH-940 seems promising, as does the Sony Z1000. Anyone know how their isolation compares?
Thanks again!