Well, it sounds like you are very happy with your set up. The only issue I see and it isn't really an issue is that the crown gain knob should be at 100%. The gain knobs on these amps are for limiting the volume for commercial setups where they have a lot going on. You would have the crown at 100% and control the volume elsewhere in your setup. BUT, if you like it as is, you can leave it. Thanks for the update on the set up. It is like I did it and I didn't have to spend a penny! Living vicariously through others, the ASR way!
There is some history of users complaining of hiss with the XLS series... particularly with high sensitivity speakers - in almost all cases, this was resolved simply by turning down the gain slightly - I keep the gain on mine down at 75%.
As long as your pre- can put out the V to push the XLS to its rated output, the gain adjustment should be placed to optimise signal/noise and distortion...
So where the gain setting is optimal will depend on your particular pre-amp / AVR, and its behaviour.
If your pre, provides the best results when pumping out high V, then the gain should be lower, if your pre is best when pumping out low V, you will need the gain higher....
It isn't a one size fits all question/answer.