@earthbound i have the XA-25 also, it sounds really good but the Sit-4 takes it to the place you want to be. I use the XA-25 in the front mains of my home theater. For the final solid state with these speakers it’s the Sit-4, my old ears give me the measurements I need..plus the resistors you have on the back for adjustments is all I need..
I use the XP-12 Pass Labs preamp