Here is a other review link about Starkey SA-43 : http://inearmonitoring.files.wordpress.com/2009/11/sa-43-review-lyd-og-bilde-november-2009.pdf
Had none issues about the filter, it is well none and fits right in.
It`s to expect from one of the world leading hear aids company.

(Borrowed from starkey)
As you can see the filter infront, use the filter for concert or
hearing protection and still maintains the natural audio fidelity without distortion.
You cant use as same time with ERM monitor.
SA series sounds better then ERM, but ERM isnt that bad either.