I've tried many IC's with my Pass X-250 to Sim P-5 connection. I ended up sticking with Audience AU-24 XLR's. Great synergy with the X-250. They're the best I've used (including Cardas Golden Reference, Neutral Reference, Acoustic Zen Matrix and Silver Reference, Ridge Street POIEMA (a close runner up) and the Pure Note Epsilon Reference V4 (another Excellent contender).
Enjoy!
Enjoy!