I will be auditioning the CAT Ultimate/power amp combo this coming W/E. Not vs. an AR, though... Also, speakers will be A-Physics (starting with Avanti, Caldera, Medea; as far as the amp will go), rather than your Wilsons.
Note: this will take place at the dealer's -- NOT home.
I you think my impressions are relevant with this set-up, don't hesitate to contact me.
BTW, I love the CAT pre!