Help w/ preamp

Hey guys!

A while back I posted about my search for an amp...I got a ton of great suggestions and had decided on demo'ing Parasound and Anthem. I found a local Parasound dealer here in Pasadena, and I was FLOORED. I have been using a Marantz SR 7011, connected to a full Martin Logan setup: Ethos fronts, motif x center, motion 40 rears. I felt like I had never really heard my speakers once they cranked up the Parasound. I told them my budget and they introduced me to the KRELL CHORUS 5200....man, oh man. They had a floor model for sale, as they were making room for a new 7 channel. The sound was similar, but I felt like the bass had more punch, and they made me an amazing deal - something I have yet to find online (lucky me I suppose).  So, after that long story...here's a few questions:

1. I am currently using RCA instead of XLR, as the Marantz AVR doesn't have both. I am sure I am losing some audio quality here correct?
2. I am thinking about adding the Martin Logan AFX (atmos) speakers soon - but since the Krell is 5 channels, I would have to run them through the Marantz - is that a "bad" idea?
3. The store I bought the Krell from recommended I swap to the Marantz 8802 as a pre, and use a 2 channel amp to power the atmos - something like a Parasound A23, which I see fairly cheap on here. Or, I could just sell my 5200, and buy a 7200 (there's a good one on here).

I guess, my main concerns - will the sound seem "different" or "uneven" getting amplified from different sources? Whether it be Krell + Marantz, or Krell + Parasound. And, would I be losing quality running anything through the AVR (I know they are just atmos speakers, but still) as opposed to using a dedicated power amp?

Any and all advice is appreciated. Thanks@