Look at the impedance graph and the paragraph below:
"The above graph shows the electrical behavior of the Aria Evo X No.4. Focal specifies this as an 8 ohm nominal load, but that looks like a real stretch to me. They also specify the impedance minima to be 2.5 ohms, but I didn’t measure it to be quite that low. While most of the range stays well above 4 ohms, the dip at 100Hz might hit cheaper amplifiers pretty hard, especially if played at loud levels. The problem is that the range around 100Hz is heavily used in all types of content, and the dip could pull a lot of power. This will create a lot of heat in amps that don’t have good thermal management. Premium AVRs and outboard amps specified for 4 ohm loads should be fine with these speakers, but I would definitely not run them on budget AVRs. This shouldn’t be a problem since I don’t think many people buying $6k speaker pairs will run them with entry-level AVRs.
I measured the sensitivity to be 89.5dB at 1 meter for 2.83v which is a bit off from Focal’s spec of 92.5dB. However, they don’t state the voltage or context for their measurement.. Either way, this is a big tower that doesn’t need a ton of power to get loud."
Members seem to be trending towards class D amps these days. They tend to be smaller, run cooler and are more energy efficient. Look at amps from ATI, Buckeye or Outlaw to start.