I am always surprised by what others consider "Quiet." I'd suggest that for Mac-centric products, quiet is nearly silent.
This unit is fast - ultra fast - and a great purchase for video editing or sample libraries for music production; but it has a fan, and it's loud. You'd think the fins on the enclosure would be enough to the cool the SSD drives, but apparently not - it emits a loud, constant whirring thanks to the teeny fan that they shoved in this thing.
I'm reviewing it in this manner just in case anyone is interested but expects it to sit in a quiet studio. I'm disappointed.