Hi
I' ve listened to them for 2 days , with a passive preamp
I own a modded Panny 45 ( and have had a Tripath-based amp 3dLabs ) , it has a lot of qualities but the UCD180 is better : more natural , more airy and more linear
no need to search for a special cable or filter , or burn-in , the music is quite simply there
you can find them here :
www.hypex.nlabout them : classd.org
Al