I am having a hard time getting a distinct sound from the backs...
Sounds like a combination of areas need to addressed.
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The Rotel RMB-1095 that we reviewed a while ago had a laid back high end, and the 1075 continues in that mold."
https://hometheaterhifi.com/volume_8_3/rotel-rmb-1075-power-amplifier-7-2001.htmlA laid back high end doesn't work as well with modern Blu-ray disks, all those quick, sharp directional ques will be subdued. Back in 2001 the Rotel sounded great because surround sound was closer to a matrixed mix instead of the Dolby Atmos object oriented sound that arrived around 2018.
The X-LS are probably less bright than the B&W so you will notice the drop in detail but better overall sound quality.
The Rotel RSP-1570 doesn't have room correction so you will manually have to set the distance and levels with sound meter.
New processors have advanced menu frequency adjustments to fine tune the speaker to your room if the highs are too soft.
I lowered the volume of the LCR speakers in the processor menu which made the rear speakers louder in comparison, I call it my "Dune" adjustment. I saw "Dune" in a Dolby Atmos theater and realized my surrounds were not adjusted loud enough. Lowering the LCR volume gives the rear speaker adjustment more headroom so the settings aren't maxed out. Even advanced computer/microphone room correction is only a starting point, fine tuning has to be done by ear.