While I share the considerable skepticism here for obvious reasons, I try to keep an open mind so looked into it a little and found this review of the QSA fuses where the reviewer was likewise highly skeptical but was fairly dumbfounded by the difference QSA fuses could make and that they scaled up considerably as you go up the line. This, to me, and along with the OP and what @willgolf have found at least adds some element of potential credibility here, and the thing is they offer a 30-day trial period so for $250 why not try?!? Anyway…
https://www.stereotimes.com/post/quantum-science-audio-series-fuses/
One suggestion to the OP — I’d try pulling your monitors out another foot from the wall to see what happens especially for 2-channel sound. My guess is you’ll get better balance, increased soundstage depth, and the speakers may even disappear a bit better. Hey, it’s free if you haven’t already tried it. FWIW.

