In the case of ATC, they also recommend a minimum of 75 watts, and it’s no coincidence that their least powerful amp is 100wpc. As explained above, of course it will work with ten watts, but that’s not really using them as intended.I also heard that there is difference in the “quality” of watts. They differ from amp to amp. Low does not mean weak in some cases, says my local dealer.
I don’t hear loud music, so if 20watt class A is enough I will consider it
It‘s entirely your choice, but you seem to be flailing around somewhat. One moment you need 300 watts, then 20 will do!