Sir, I’m sad to say, you and his schools have done a lousy job of teaching your son how to think.
He ought to be able to figure out his existing 300wpc is far more power than those highly efficient speakers need, even in a very large space. And, he’s not smart enough YET to figure out he will spend MANY YEARS wishing he did NOT listen too LOUD!
He is probably damaging his hearing, as many of us regrettably did! ..........................
I agree, go TUBES. Want McIntosh, get a vintage McIntosh Tube Preamp and Tube Amp, I would chose the mx110z preamp tuner/preamp (like mine), and the slightly larger MC2275, 75wpc, more than needed, but in case he changes to less efficient speakers in the future.
Got a fetish for big blue meters, get over it.
best of luck,