All I know for sure is that the specs which are rated in terms of “per foot” or “per meter”, seem to favour using monoblocks close to the speaker. So close that the speaker cables never get to the floor, always seems to work for me.
The only point in time where electrical energy does NOT flow is at that point in time when the voltage passes from the +ve cycle to the -ve cycle - the rest of the time there is energy transfer
I think that the input voltage needs to higher than the rail voltage (and maybe a diode drop of two extra…
So it is like 10 degrees either side of the zero crossing where that voltage is not enough to flow into the power supply.