There are many sceanrios where a listener could not tell there were changes to a system. Of course that does not mean there isnt a difference or it isnt a desireable difference. Much like swapping out phono cartridges, if you walked out of the room while it was switched, you may not realize what's different when you returned. Would any of us say phono cartridges all sound the same based on that? Many products in consumer are like that, requiring a very careful comparison and a educated listener. @erik_squires , you are a very educated listener!.
Working in this industry full time, where differences are a constant challenge in diagnosing problems in service (client heard something you cannot replicate) or assessing value of something new, you can be fooled but usually scinece wins. Which is why we have a $10,000 Audio Precision sytem with calibrated mic to measure things. The science behind active vs passive is conclusive and not debatable, unless you elevate your own perception as the superior test. Demos are contextual audible comparisons with a tremendous number of variables. For some, once their own perception is satisfied, even if inaccurate to science, they are happy and the search is over. Sort of a parrallel to the way we prefer one color over another in a car-they really do look different in more ways than color alone. And once we decide which color we like, we rarely look back.
Ive said it before, I think active expands the ability to hear changes in the system of various cmponents, not reduces them. All the elements before the active speakers are easier to hear, cables, preamps, turntables, sources, etc. thqtq's certainly my expereince. Sometimes it seems like the shared thought is "I'll buy active when you can pry my amp from my cold dead fingers". It like the amp makers marketing has convinced everyone that its worth buying an expensive amp. From a science point of view, passive being "better" than active is like telling someone from Arizona that snow tires are "better" on an all wheel drive sports car when you've only test driven them in the snow. Snow tires may indeed work better in that one condition, but certainly not all. Because you've never driven that car with snow tires in the summer on a dry road doesnt make it true.
Brad