For the crossovers I used Solen capacitors with a Hovland Auricap in the compensation network, Mills non-inductive resistors, and whatever inductors Parts Express sells. The drivers are front-mounted.These speakers sound awesome. I was expecting to give up some detail and neutrality when I gave up my Magnepans. This is not the case at all. My four Pi's actually sound a lot like the Maggies, but with much better dynamics and more bass. My amp is a Jolida 302A, modified to run in triode mode. It puts out about 25 watts with the modification, but that's enough to make things shake. A couple weeks ago the girl who lives directly above me came down and asked me to turn down the music because it was literally shaking her desk. So these speakers are excellent for both critical listening and for high SPL's. Plus I have the honor of being known as "The Guy With the Really Big Speakers." :-)
Mike Borzcik
PS- Has anyone heard the four Pi's with a Decware Zen amp? I'm thinking of buying one of their kits and am interested in hearing how they work with Pi speakers.