How would I know I would not experience similar issues with these power amplifiers as I have with the Classé and Parasound? Ordering Audiophonic, Nord, Apollon or similar would likely have to be done from abroad, so if I did experience similar issues returning it would be a pain (also custom costs will be quite significant).
If I remember right you just need a 2 channel amp to power one of your surround/height/Atmos channels so why not just buy a $89 Fosi or similar class C chip amp and be done with it. If that hum, that I doubt very much, just send it back with a good reason (assuming you buy from Amazon.com).
There is nothing wrong with those mini chip amps, they sound as good as the Parasound to me ears and mic. Hard to believe but true, people just can't shake their Placebo prone ears/brains (too me a long time too...).
The much more costly way is of course to buy from Audiophonic, Nord, Apollon etc., and if you experience similar issue then just use their return policy, but yes you may be subject to custom cost if your country is not part of the EU, but is it?).
So I really thing you should try the Fosi amp first as that would limit your potential loss in shipping/custom costs. If still get the hum then you really should try the Benchmark RCA to XLR cable and see if it works with the Classe, I still think even that cheap Monolith or Ghant Audio pairs will.