I ran across this page in the Phonak Custom Products reference guide. It says at the bottom of the page that Cerustop wax filters are not suitable for cShells with UP receivers.
I have a pair of UPs with Cerustop filters in my ears right now that I got with KS9s. When I remove the wax filters, my word recognition in Calm improves. My audiologist says that Cerustop are the only option. I see her tomorrow.
Anyone have any experience with this? I may be ordering UPs for my new iSpheres tomorrow, because I think the Ps I got with the first fitting may be causing clipping.