I'm about to build 5 of my Micros (same driver) for a customer that will be using the X25 receiver. He's also getting a small ported 8" sub. I think this will be an excellent little system based on what I've heard of the Panny units and what I know about the 871S.
Also, depending on what type of enclosure you're going to build, I'd suggest picking up one of the plate amps from Parts Express to mate to the Shiva.
