So at the moment I'm learning the first movement of the Pathétique Sonata by Beethoven. The main problem I'm having is with the left-hand accompaniment which is similar throughout much of the piece, where you have to play alternating octave notes. I can play those notes fast, and I can play them quietly, but I can't do these two things at the same time. Trying to play faster just results in them being too loud, which doesn't sound nice.
Obviously, when it comes down to it, practising slowly then building up speed while maintaining dynamics helps, but does anyone know anything else useful for playing quietly at a high speed? I know already that you should keep your fingers near the keys all the time, although I don't know how effectively I'm doing it.