ProAc have always worked well with more modern Naim amplifiers, so you'll not have any issues there. They're fairly easy to drive and don't represent an awkward load, but they do like control, which the XS will provide. Bear in mind that there is an XS2 due later this month.
I can't comment on the Clearaudio as it has been a while since I've heard one, but it looks to be around the Michell Gyro SE price point, so should be good enough for the system. I would suggest trying a few decks with suitable arms/cartridges to see what you like the sound of.
As mentioned, you'll need a phono stage with the XS/XS2.