While I'll agree with Sam's article about passive pre's I did have a chance to listen to that particular passive unit for several weeks and it was extremely good but I still preferred Steve McCormack's VRE-1b pre-amp and by a wide margin, which by the way only puts out 6dB of gain. There's an axcellent review that just came out here:
http://www.ultraaudio.com/index.php/equipment-menu/284-smc-audio-vre-1c-reference-preamplifier
(Dealer disclaimer)
http://www.ultraaudio.com/index.php/equipment-menu/284-smc-audio-vre-1c-reference-preamplifier
(Dealer disclaimer)