I`d much rather do that I guess, but then, I need to find a different amp to power the bass section of my speakers to be able achieve this correct ??
As I understand it you are looking to configure something like this...
Biamp/High - Atlas Magnum - 200k
Biamp/Low - ** TBD ** - ??k
Sub - 10k
If so, then yes, look for a Biamp/Low with impedance of say 47k or higher.
Same could be accomplished by finding a higher impedance Sub amp but I suspect that will be harder to find based on the specs of most sub plate amps that I'm aware of which all tend to have low impedance. Unfortunately the lowest impedance device drives the bus on this subject. Finding a sub with a higher impedance would help a lot.