Never tried the DT990, but I had the DT880 for a while. I can definitely say the treble is much smoother and easier to listen to than the DT880. I'd say it's only a bit brighter than the 650, just with better air and extension. The 650 is one of my favorites, so I think you would really like the Elex. I haven't heard the LCD2, but others have said the Elex is brighter than the LCD series but with a more midrange focused sound signature, similar to the HD650. The 800S is another great choice, but they do still have some heightened treble that may be too bright for you without EQ.
The Elex does incredibly well with EDM and other bass centered genres, because you can really feel the physical impact thanks to those speaker-like drivers. The dynamics are just insane with them, much better than the HD650. I use the Elex for gaming often, they are very good for that as well.