Stereophile's December 2013 issue has an exceptional review of the MOON 850P Preamplifier. In the same issue, the 880M mono power amplifier and 810LP phono preamplifer each received "2013 Product of the Year: Finalist".
In his conclusion, Brian Damkroger exclaimed: "It's the most transparent preamp - or audio component of any sort - that I've heard. In my room and system, the 850P provided a crystal-clear window on any contribution from or change made elsewhere in the system while seeming to add nothing of its own. It's handsome, exquisitely well built, wonderful to use, and provides enough flexibility and functionality for any system I can imagine. I found the 850P to work beautifully with a wide range of equipment; combined with the matching 880M amps, it formed a system as good as or better than any I've heard anywhere, at any price.
You can read the online version of the review here.