^^^what he said...he's right. Even without AAS, you you lift heavy with low reps, you will end up putting slabs of muscle on.....since with strength comes mass. The two are directly related: bigger muscles are stronger. That is the whole principle behind weight training...and as your strength increases, you increase the resistance by increasing the weight to force your muscles to continually grow in order to compensate...
If you don't want mass, then stay away from AAS, and do light weights to failure.