If you're considering those, I'd strongly recommend adding the Adcom GFA-5802 to your list. Having heard the XPA-2 for a little while and Adcom 555, 5500, 565, 5800, and 5802 extensively, the 5802 is the winner in my book. That thing will run at full power at 1 ohm for a day and not blow up. It's a beast - an absolute beast. There may be better amps (I've hear a few), but they cost >= 500% more. I personally run tube amps, but in the budget SS category, I can't give a stronger recommendation.