I have used Rena pumps, and found them to be quite quiet, but I recently bought an interpet airvolution (dunno the model, just that it is the biggest one) for my 55g. it powers a 45" air curtain, and an airstone, and boy is it powerful!! It also has 2 outlets, although neither is variable which is a shame, you'll have to use airline clamps to vary the output on it! Pretty quiet as well. The volume will also depend on the type of airline you use (go for the silicone stuff) and how you have it in the tank. My aircurtain has small ceramic weights along it's length to hold it down, and if any of them are touching the glass, it makes a hell of a racket!!!!
I also have an Elite 801 pump (dunno who makes it) and that is pretty quiet too.
I would say the airvoluton is the best of the 3 for power and volume!
