You could use a tube preamp or a tube amp in pre amp mode so you can retain the E9's excellent power capabilities.
It'll add tube flavor to your E7/E9 setup, you'll make use of everything you have and the Tube Head scales with 1000 dollar amps for sure. There are a couple reviews on it if you dig deep!
I think it'd be good option to keep the excellent driving power with your Grados yet add tube warmth.
Firestone Audio has an excellent reputation here on the boards.
Just something to think about.