Stunning tank you have there, and no, not too many rocks, just keep an eye out for any anaerobic bacteria growing underneath them. It may be a good idea to give them a quick shuffle around every now and then.
Also, in regards to the noise, what on earth were you trying to do, inhale the tank?
really nice looking tank however i think i spotted a red tail black shark there?? as they get bigger they will terrorize it haha i really miss my mbuna and i am in the middle planning my next mbuna tank.... love the rockwork (it is on the glass isnt it and not the sand?) would hate for the little blighters to under dig and collapse it.