This is the famous early version W5 rated at 175WPC with THICK GREY (pewter) faceplate and gold SimAudio badge. The W5 is no longer made as it would compete with the $15,000 W8 (much larger power supply than W5.3 and W7). It is also very smooth sounding compared to the 190WPC version and newer designs. Its designer, Jean Poulin, can still be reached at Simaudio today (see http://www.simaudio.com/contact.htm).
I am the original owner (after the dealer) and will answer any questions you might have. It sounds very nice and never ran out of power, but I had to switch to monoblocks due to domestic situation. The face, top, and back are mint. The only flaws are a few short scratches on the sides of the legs - not noticeable in my opinion but I can send you pics. The warranty is still in effect until Feb 2013.
Stefan J. Drever
"As can be seen from fig.13, the Moon amplifier proved to be a powerhouse on this test, almost doubling its power delivery each time the load impedance was halved. For a standard 1% THD+Noise, it delivered 233W into 8 ohms, 460W into 4 ohms, 865W into 2 ohms, and a staggering 1480W into 1 ohm. No wonder Kal Rubinson found the Moon W-5 to control the bass panels of his Apogee Duettas so well." — Thomas J. Norton