According to Pass Labs, the X600s are class A operation up to 100 watts continuous and 200 watts peak, going class AB the rest of the way up to 600 watts. The X1000s are class A up to 90 watts continuous, 180 watts peak, and class AB to 1000 watts. Yep, the X1000s are out of class A before the X600s, probably because of heat dissipation considerations.
They both get real hot to the touch, but won't burn you. It's hot enough that you have to think about placement, ventilation, and room temperature impact, especially if you leave them on all the time to avoid warm up issues.
One last observation, the X1000s have a special kind of power plug that requires a special kind of power socket. This makes it hard to use aftermarket power cords, power conditioners, and your standard wall socket. Now, that takes real commitment.
