I did, and once I heard the T90 compared to my DT 990, I sold the 990 and got the T90. The bass is tighter, better defined.
The kids are a bit more lush. Of course once I heard the T1 (gen 1), I felt the same way about the T90. I'm not a big fan of the T1 gen 2.
Once you have a DT990, improvements are incremental. If you never hear a T90 or a T1, you will be perfectly happy with the 990. Your problems start once you hear something better, even if only a little better. Then you end up having to have everything!
You have a few choices (as I see it).
- Delete your head-fi account and be happy with what you have
- decide you are insane (like the rest of here) and either upgrade to mid-fi, then to upper-mid-fi, then to summit-fi
- just upgrade now to summit-fi