Can your Onkyo provide a pre-out for the amps? With such sensitive speakers what's the goal? Why do you need a power amp and why Emotiva particularly? The XPA2 is 300wpc isn't it? I wouldn't call it an investment particularly, if you're going to sell it it would be at a fraction of its cost

I think the newer amps from Emotiva are using
switch mode power supplies, fwiw. Personally I'd be looking at class D amps instead (I use Crown XLS, but Hypex or Purifi based power amps look very nice if I wanted to spend more).