73max OP
Just look at amp reviews on Stereophile and in the bench tests you see they test them into 8 4 and some times 2ohms if they can handle it. Doubling the watts from 8 to 4 to 2ohms is good current, but no amp can double exactly without losses, so instead of 2 x the wattage 1.8 is fine.
Look at the watts they get of of it EG
at 8ohms (eg 100w),
4ohms should be at least say 1.8 x higher (180w)
2ohms at least 1.8 x higher again ( 324w)
This is the sort of amp you should look for, one that almost doubles it’s wattage for each halving of ohms, with those loads that your speaker gives to get 100% of of them.
Your Classe ones look good, maybe yours just has noisy fan bearings or your filters are blocked?
Cheers George