You try streamers and cables and you have now stopped doing that because "Why would i keep wasting my time testing things that have no scientific basis?" You want to know what you get beforehand but you won't waste your time testing things? Is there any real scientific basis for a claim that cable A sounds better than cable B or that streamer X sounds better than streamer Y? I would love to know, especially with respect to the cables. You could also say that there is no scientific basis for one well made dac sounding better than another. If you want audio science, then this is the place:
https://www.audiosciencereview.com/forum/index.php
"Like a 5k headphone amp for 32 ohm headphones." So, are you saying that as long as the amp can drive the headphones nothing else matters? A $300 amp could easily drive 98% or so of the headphones on the market. Are you saying that spending more than that is a waste of money? Most people here will tell you that there is a lot more to an amp beyond the primitive ability of being able to drive a headphone to the level you listen at. I myself will say that based on my own experience. I normally listen at levels that my phone could drive my headphones to but I much prefer using an amp. Is there any scientific basis to this? Not that I am aware of, it just sounds better to me and that is what it all boils down to, does it not?
Is there an "end in sight"? Absolutely not, you can move forward, backward and sideways but there is no end in sight. If there was we could all just pack up and go home. The party would be over.