So how much do you think the placebo effect impacts our listening preferences?

Have you ever worked in studios, with audio professionals, or even spoken to industry leaders?

for those who don’t know, @soix has been in and around the high end hifi industry for many many years, in fact wrote professional equipment reviews, has terrific ears, thus has broad and deep experience and knowledge in this field, and actively shares it with other users seeking guidance on this board

just sayin...

@soix doesn't call out others' statements often, nor whimsically, and when he does, most readers here take notice

IMHO the placebo effect happens more for subtle possible improvements than big ones. When something hits you obviously when you listen for the first time, that is when you know you have something. Unfortunately (or fortunately) many changes happen, many records get played, and it is very hard to know what or how much happened when.

Also, it is very hard to remember how something used to sound.

I’m all in. Just wanna spend more money on this hobby and feed my head that it sounds better Irregardless of the actually facts. 
100 percent Placebo effect with no adjustment and not afraid to say so…hypothesis confirmed

there i said it…now let me polish clean vinyl and listen in a dark music room. 

Ridiculous

One other point - if you know something is better sounding than something else, by recommendation of someone you trust or universal acceptance, sometimes I'll just go for it knowing it is better. For example, I was told by Ron (Martin) Sutherland himself of the Phono Stage company and creator of Martin Logan several decades ago, that my phono stage would sound better with a linear power supply versus the switched one provided as standard. He had just started offering the upgrade of his trickle down technology from a phono stage costing 2.5 times as much as mine. It was a little less than half of what I got the phono stage for, but he said if it was his brother in law, he would tell him to do it, so I just did it. He even helped me install it so I wouldn't have to pay 2 way shipping to Kansas.

Could I tell afterwards? Not specifically, but I had also recently upgraded the interconnect from the PS to the amp, but sometimes knowing it is better sounding gives you peace of mind even if you didn't prove it specifically for yourself.

Perfect example - rollerblocks isolate components and also transfer vibration out of them. Inside them are ball bearings of certain specifications that make the box float. The new base level (formerly one top from the base) has 10 parts per million of imperfection in the shape/quality of it, and the highest level one, called a "super ball" (I kid you not), has 2.5 ppm, or a 75% reduction in imperfections. The cost of this upgrade is equal to the entire cost of the base rollerblocks with (the newly upgraded) standard bearings. Some people will buy the super balls based on the owner's recommendation knowing they are the best and have that peace of mind. Bear in mind that the previous improvement to the 10 ppm was down from 60 ppm, or an 83% improvement. Talk about the law of diminishing returns....This is the epitome of it, but he sells a ton of them for those who want the absolute best, and if I spent triple on my stereo,  I would probably get them. The owner did not recommend them to me based on my system, so he understands how high resolving a system you need to hear or appreciate the improvement. This is the case with fuses, power cords, etc.