Preamp Outs on AVR

I have a Marantz SR 7008 and have the preamp outs going into a Rotel
Power amp. My question is how does the settings such as speaker size, crossover settings
Equalizer, etc work on the AVR when the amp section of the AVR is not in use and the speakers are connected
To the power amp not the AVR. I thought the preamp out was sending unmodified signal to the amp so
I’m curious how this works. Actually more than just pure curiosity I’m thinking about upgrading my system
and trying to figure out where to invest for maximum benefit. My speakers are ML. Motion 40 and amp is
Rotel 1582 MII @ 200WPC