Regarding some not being able to discern streamer quality, I usually boil it down to the fact that those people’s systems are not resolving enough (like putting a $9K phono cartridge on a $1000 turntable / tonearm), they aren’t the critical listeners, or the upgrade in sonics isn’t worthwhile. But for those with a highly resolving system who are looking to make the best out of it, a high performance digital source should make a significant impact.
This explanation is thoughtful and well reasoned in my opinion. With a resolving audio system, how could one not notice improvement with a better source component?
Charles