I realise that this is nit picking, but this point (of which I was unaware, as my budget runs to neither KEBs nor 350s, so thanks for the info) is surely just an aspect of the way in which the software handles the relationship between the Exakt engine and the speakers, in which it, so to speak, takes the intermediate amplification as a given. The servo bass on the 350s, though it obviously involves amplification, is part of the speaker. I think that the OP was looking for Konfig-style settings related to the amplifiers, and there aren't any of those.
My reply wasn’t meant as nit picking, but to mention were gain factor differences are currently handled. I’m sorry if you’ve perceived this as nit picking. It wasn’t my intention.
Here’s an excerpt of the Akubarik filter:
<gain>9.5</gain> // overall gain
<gain>-1.5</gain> // channel specific gain
<gain>2</gain> // channel specific gain
The overall gain is used for providing the same loudness for different speakers at the same volume setting of the DSM. The channel specific gain is part of the crossover design. If different gain factors of the amps in use need to be taken into account, these gain settings needs to be adjusted.
Of cause there is no user setting for doing this, but someone with access to Exakt Design might easily make the required changes (pure speculation, as I don’t know how Exakt Design actually works).