I disagree personally. I don’t think they need to be side by side to appreciate the difference, so long as you’ve ever experienced both. I miss the things that I know I’d get with better speakers when I listen on a different setup, and I still enjoy the experience, but it doesn’t move me as deeply when I feel something missing. And I don’t think it’s (all/entirely) placebo. A subwoofer that reaches 10hz lower, moves more air, and fires faster gives you a lot more to hear/feel/appreciate, and to me really changes my physical and emotional reaction to music.