With the introduction of equalizer in Amarok i think it would be a great idea to be able to assign different equalizer profiles to songs/albums and invoke them automatically with every new song/album (would it make amarok a lot slower?).

That's already work-in-progress. Or at least, we have some plans and ideas

Yeah, its in the idea stage at this time. Or to be more exact, this feature would be a 'side effect' of something more general I am pondering

...now to find the time to actually do some of this stuff...