I have the STR preamp and think it's excellent. As @audiotroy suggested, you might consider that, rather than the integrated. You could mate it with a Benchmark amp or Anthem's matching STR amp or, really, any amp that pairs well with your speakers.
Whether the benefits of ARC will outweigh any losses due to A-D-A conversion of analog sources will depend entirely on your system, particularly the speakers and room. I have found that in general room correction is beneficial, and after using several devices that have it, I consider the STR to have the most transparent version I've tried. All the processing is done at 192 kHz.