I have 3x PA3 not SA3, but I’d assume it’s very similar if not better since it has less components inside.
Anyway they are the amps that gave me the lower noise on my system, with 98 & 95db midranges and tweeters, active crossover.
So no toroid buzz or hum, and I can only hear a hiss with the ear at 1cm of the mid cones, nothing at 10cm, and nothing at all on the tweeter.
I tried a bunch of amps among the relative best for low noise, like hypex nc, ice asx, an old class A and some AB, they were all too noisy in my case, buzz or hiss.
Topping pa3 were dead silent, but unusable as power amps.
Tested an AXA25 and it didn't have any hiss, but was buzzing from the power supply.
But I'm not sure it’s helpful, as things can be different with your setup / home.