Check out the November issue of Stereophile where you will find a colossal review of the MOON Evolution 820S Power Supply driving a MOON 650D DAC, by Michael Fremer.
MF's conclusion says it all: "My advice to owners of Simaudio’s Moon Evolution 650D: Go to your dealer and get an 820S to take home and try. Put it on a credit card if the dealer doesn’t trust you, but be prepared to drop $8000—I don’t think you’ll be returning that 820S to the store. Yes, adding an 820S almost doubles the 650D’s cost—but in my opinion, adding it more than doubles the 650D’s sound quality, which will more than double your musical enjoyment. And, as in the Hokey Pokey, that’s what it’s all about."
You can read the full review here.