Rather than a computer for streaming music, for WAF consider a tablet with digital output to external DAC perhaps. Or I find analog sound out from my newer Iphone 6 running good quality streaming software to be very good quality these days. I use Plex to stream from my music server mostly with my systems. Plex runs on browsers, tablets, phones, and various other common platforms. Other apps that stream from internet music sources do as well.
Applying just moderate caution, I’ve used teh 500 w/ch BEl Canto ref1000m amps with all my speakers, large and small, at all volumes with no issues.
My speakers range from tiny Realistic Minumus 7s on the deck to slightly larger Triangle Titus to slightly larger Dynaudio Contour 1.3 mkII to somewhat larger OHM 100s to my big OHM F5 series 3. Sounds great with all.
The rule is to experiment with high volume gradually, especially with more dynamic recordings. You are usually good. If you hear any signs of audible distortion, then back off until the cause is clear and addressed.
500 w/ch is probably overkill for the more efficient Triangle Titus speakers, but I think the power benefits all the others to some degree as well, though I could probably get by with less.
The big OHM F5s in my larger room are teh only ones where I think I might feel I was missing something. The smaller OHM 100s could probably get by fine in most intended rooms with a good clean 80 watts or so. Once I used 180w/ch TAD Hibachi amps in place of the BCs when they were out for service. They did great with the 100s in my 12X12 office room. The big F5s in my larger listening room did very good as well but they definitely ran out of gas a tad in comparison at some of the higher listening volumes I do in there.
Remember that power demands increase exponentially with volume so having extra power in reserve when needed is always a nice insurance policy at minimum I find.