best premp for a pair of pass aleph 30's?

Recently sold my forte and bought a couple of the pass amps, using on aragon 18k pre right now, paradign studio 60's v3 that are soon to be replaced. Right now music is very bright..im guessing from the metal dome tweeters, bass is tight and punchy with the new amps. Considered going to a tube preamp maybe eastern electric. My question is what am I going to gain with the tube pre? Would like to keep the pre ss. Thanks