Can someone show a photo of the inside of the 990? Why is the thing so big? What is inside? Is it a huge power supply to make it noiseless?

Sorry, mine's already moved into the rack and I don't like the idea of unhooking it and hooking it back up. Maybe somebody else can grab a few shots.

Keep in mind that the Model 990 is based on the Sherwood P-965, which was itself developed with the idea of being a single chassis that could be used for either a processor or a receiver (the R-965). The R-965 has binding posts where the 990 has balanced connections and DVI switching; the P-965 has blank space there. This particular design lineage is presumably responsible for both the height and depth. Shaving off some depth would probably have been quite convenient for many people, but it would have required additional re-tooling at the factory to produce the shorter chassis just for the 990. On the plus side, if you can get it in the rack, the extra height makes the connections somewhat more conveniently spaced out, easing the burden a bit when it comes time to plug everything in.