Help settle a streaming argument!

based on my personal practice and  observation, the better are your amplifier and speakers, the better they do their job and these differences somehow diminish. 

Or one can interpret your observation a little bit differently. In that, upgrading your speakers AND amps yield much better, impactful, unmistakably audible, results than upgrading your streamer alone. Interpretation which I fully agree. 

Yes indeed. If you can afford a V8 car, and paying for gas for it, go for it! No question better than a four cylinder car. Going from that V4 to the V8 is unquestionnably the most noticable outcome. However, I am sure people with V8s try to squeeze as much as they can from them, thus all the mods, and souped up upgrades. And there is notthing wrong with it too, if you are a car guy (not me).

I like to drive fast but prefer V4 car with turbo to V6 car, which I also have but do not use it often. V8 feels somehow better but, for me, it is completely unjustified, and anti-ecological

.... or you can drive a performance electric car, and get the best of both worlds. Amazing (horse)power, and instant / powerfull torque (and not anti-ecological)

For the moment, I see one major obstacle, the number of miles that one can run with a single charge of the battery. 

You can install a charger at home and it's like having your own private gas station in your house. Full "tank of gas" every morning. Unless your daily commute is hundreds of miles obviously. Better yet, free charging at work (car charges itself while you are working). Or plenty of fast DC chargers all over the place (where I live). Not an issue

Those of us who have actually done the experiment, switching from either a computer or low quality streamer to a high quality streamer, have heard an unmistakable improvement in sound quality. Even if we don't have the technical know-how to explain it. 

Bingo!

For the rest ... ignorance is bliss