I currently have the W3 Moon and W-7. The W3 sounds very good. The W-7 is a later design and sounds more refine with better soundstage but lacks some of the excitement of the W3.
I also compared the W7 sound to my Cary Six Packs tubes, and the W7 actually sounds better but again the W7 lacking that bit of an edge. It could be my power cord ... idk ... but I use the same power cords to my W3 so that can't be true.