Got one of these about a month ago from Pacific Valve for $105 or so - incidentally, after I bought mine, they must be running out of their stock or something because their price jumped up about $20 (!). Anyway, thought I'd give my impressions:
System = Windows 7 Ultimate-based self-built PC with foobar2000 through cMP shell + Fidelizer 1.6 for playback -> Kimber Kable USB Cable -> Olimex ADuM4160 USB Isolator with 12V wall wart -> Furutech GT2 USB Cable -> Keces DA-151 MK. 1 DAC -> Blue Jeans LC-1 RCA Interconnects -> Little Dot MK III w/ GE "5 Star" tubes -> Headphile Senn V2 BlackSilver Cable -> Sennheiser HD600's
I hadn't done any power conditioning or power-based tweaks prior to the purchase of the Audio-GD outlet, with the exception of some "Iron Lung Jellyfish" Hospital-grade power chords for the Keces and Little Dot, which seemed to make a subtle difference. At first I was forced to use the stock power cable that came with the power filter outlet, which really is dismal in terms of gauge and build quality. I also need to replace the actual in-wall power outlet I'm using it with, since it has terrible grip and has been painted over, one can tell, many times (I live in an apartment). The stock cable for the Audio-GD would cause some audible buzzing/electrical noise in the Audio-GD outlet itself, which, of course, is not a good thing - this only happened if I was manipulating the plugs. All of this prompted me to buy a more robust power cable, which I found on Audiogon in the form of a used Valab "Super High Current" cable which was really thick.
Even with the stock power cable, when I fired up my system, I could immediately tell a difference. At first I went with the Kingwa-recommended DAC plugged into the -70DB socket, amp into the -50DB socket. I used one of the "Direct Output" sockets for the Olimex ADuM4160 USB Isolator's wall wart. It's amazing how much this thing can "color" the sound, and I've done a lot of swapping around. So far, I've settled upon the aforementioned combination of DAC into the -70DB socket and amp into the -50DB, but there have been times where I've put the amp into Direct Output. -50DB for my DAC sounds more "colored," almost fuzzy than the -70DB, so I've found that to be a bad combo. The -70DB for the amp seems to really reduce the amp's overall gain/volume, so that was also a no-go. Again, however, I kept finding myself switching around the amp between -50DB and Direct Output. At times, it seemed like -50DB was too "revealing" - lower-encoded MP3's sounded pretty awful, almost staticy, and I was getting some listening fatigue, whereas FLAC files etc. would be less noticeably inferior.
With the -70DB, -50DB combo, soundstage seemed to open up really, really wide, giving recordings an almost ethereal quality, and the warmth of my Little Dot's tubes was really accentuated - most recordings sounded REALLY analog. Some negatives, besides the revealing quality, is general harshness on some recordings (again, poorer recordings were more susceptible to this) especially in the lower frequencies - which seemed odd, given how simultaneously analog/warm they sounded, and some diminishing of the "impact" and/or perceptibility of some higher frequencies. While the soundstage seems wider (and, at times, "taller"), there is also a strange sense of instruments getting "smushed" together in some recordings - I still had a sense of distinctiveness for individual instruments, but their tonality all seemed very similar - having difficulty describing this. Some dynamics would return if I plugged the amp back into Direct Output, at the expense of the soundstage, ethereal quality, and analog warmth I just mentioned - it sort of "flattened" out the sound to plug it back into Direct Output, sounding much more rounded off, but also much more forgiving of a given recording's bitrate etc. My system is incredibly sensitive/revealing with the outlet, now - weird things like changing the voltage of the Olimex isolator's wall wart to 9V from 12V, for instance, is much less subtle than before, or if I turn "Dither" off in foobar things seem to improve.
When I received the Valab chord (here's a picture = http://pic3.audiogon.com/i/c/f/1305592635.jpg), many of the issues with the -50DB outelt for the amp seemed to round themselves out a bit - less listening fatigue, gain increased, cleared up some of the "grittiness" I would get on lesser quality recordings. I may have picked too high of a gauge of chord, though, as recordings are REALLY gain-y/loud now - I've gone from keeping the volume knob on my Little Dot at 9:00 to keeping it at somewhere between 8:00 and 9:00.
Anyway, I'm still playing around with it - I think I'm going to use it as an opportunity to build around the outlet, maybe get some new RCA interconnects or something. Definitely worth a purchase if you want to put some new life into your system - it makes an undeniable sonic difference.