She probably has in mind a feedback threshold that could be at a level that makes high-frequency amplification much more difficult. It is because of your open acoustic coupling (open domes?). In addition, Widex reportedly doesn’t have good active feedback control. You can try with more occluding coupling (closed domes, power double domes), but I don’t know how bothersome the occlusion effect is for you. My theory (I may be wrong) is that amplified high frequencies with small gain interact wit…
Regarding comb filtering, there was another topic worth to read.
You’re ignoring this member’s posts.