DT990 have definitely more bass than DT880, but don't get fooled with them, they don't fit well with most bassy music, they have amazing bass presentation, but they are really unforgiving headphones that simply sound thin and sibilant with most modern (non audiophile) recordings. If you plan getting the best recordings out there, (Telarc, Harmonia Mundi, etc.) most of them classical music and jazz, they can sound impressive, otherwise "Analytical and High Resolution headphones" is not a wise pick.
glad i didnt rush out then and get em bassy music is important to me, although i do listen to a lot of other genres as well
thanks for all your help! I THINK THE 770S are gonna be the winners ill will update with my opinion on em :D