For those speakers in particular most any thing will do. As they are all 8ohm they don't exactly demand hundreds of Watts ie. Stacks of power supply.
Of course you could add power if you want, but they're also quite sufficient with any moderate A.V.R.
In one sense that it true, but in another it's not. The speakers being 8ohm don't require as much current to drive, so it won't tax the power supply on any moderate A.V.R., however it will generate heat. That is the killer to most receivers. What you need to consider is how often you want to run the unit cranked and the ventilation around your receiver.
I have an infrared thermal sensor gun to measure temperatures (they cost $30 on amazon) to know how hot the receiver or more importantly the boards inside the unit are getting. Rather fun way to spend an afternoon. You will be surprised on how the heat up.
The unwritten benefit to moving some of the amplification out of the receiver is cooling as the less current pulled, the less heat generated so the receiver doesn't cook and hopefully allows it to run far longer. The modern amp fails more than older stuff as the components inside just get too hot and poof. Planned failure as who reads and follows the manual when they say give 12" clearance on both sides and 14" clearance on top (for ventilation space).
