Wilson iPad App and "E" series speakers.

I just downloaded the Wilson iPad app. It is really nice for all, but even better if you have the newer speakers. I did notice Speaker resister specs listed with many models listed as Maxx 2 "E" for example. Quite a few models listed as such. Anyone know what the E series is about? Just curious.
The E-version is simply a difference in resistors. This is to balance the sound of the system in European style construction homes (stone and thicker walls). -Debby
This would be to roll off the bass earlier? I have stone & thicker walls but a very large room for example.