I have a monica 2 dac that I bought around 3 months ago. I bought the fully assembled kit I think it was around $100 or so plus shipping. It arrived in good time and shape. I'm running it off a 13.8VDC regulated power source with no issues (I checked with yeo first). Its easy to finish putting it to work, all you need to do is solder on your input and output wires and your power supply, mount in a box and you're done.
As for sonics: I'm using it with a marantz CD6000KI and thats really all I've compared it against. Definitely theres more detail to be heard and a smoother sound (may be due to a lower noise floor, with silent passages being inky black), I know what people mean when they say a more analog sound, but I don't think that quite gets it. It seems to me to be more musical anyway, although I think soundstage wouldn't be quite as wide as direct from the marantz, but would be as deep. Its now a permanent part of my system.
Rest of system: CDP>monica2>audio innovations valve amp>quad ESL57's, CDP>monica2>LD2>HD650s.
Oh, one thing to note, the output from the DAC is fairly low, much lower than from the CDP rca outs. I'd say half to 2/3 the volume of the CDP.
Fran