This has absolutely been a civil discussion for sure. As a professional working in audio the only responsible thing that can be done is to ask clients to listen. EVERYONE from a professional recording engineer to a Doctor with an after work hobby has an entirely unique monitoring situation. Each of those people also brings their own personal level of scrutiny to their unique monitoring. It is a liability to ensure results. I would never suggest our products make you better, simply, give it a listen at home or at work and see what you think. When you take a position on these things it blows up on you both ways. First you say "it makes no difference" because on your monitoring it made no difference. Client trusts you, is happy for some time, has means to go to a different tech and says "last guy said it made no difference" tech sits him down, shows him on his system beyond any reasonable doubt there is change and then you are forever wrong in that clients eyes. You say to clients "makes a difference", client trusts you, brings it home to his monitoring, reads something on the internet, tinkers to his best ability, hears no difference and pronounces you a snake oil salesman. The advice, as simple as you can make it, is to listen. The absurdity about this entire discussion, from top to bottom, is that some people somehow perceive this advice as "build a skyscraper". It is not difficult for the curious to listen to caps and they will either hear a change or not and move on. To the guy that will NEVER spend $30 on a cap, why would that guy even CARE if something he is never going to buy works or not? The whole discussion is just so silly to me. I say this of course looking at this whole topic from a water is wet, world is round perspective. One classic example I can offer is years ago I was helping someone with a old integrated hifi from the 50's. This is when hifi was designed by white labcoat guys and the designs are absolutely perfect. Well, my friend was trying to make some changes to the phono preamp and I made some suggestions to this guy, he took my word, bought some caps, spent all this time with it and called me one day all pissed off claiming that I didnt know wtf I was doing, he spent all this time working on the thing and its just as muddy as before, blah blah blah. So I never asked the dude what kind of speakers he had and it turns out he had some modern two way thing. These old low watt amps were in every way designed to drive very very very high efficiency horns and the amps performance with modern speakers, to put it mildly, is less than ideal. I invited this guy over with his amp, told him to bring all the parts. When he got there, I first reinstalled his old components (this was a minor change he was making) and hooked it up to 3 way horns at the shop. "Whoah, sounds amazing, what did you do??" I put your old parts back in. Silence. Let me now show you what the new parts I told you to get do. Put them in. Oh wow. Whats going on here? Next day, dude went out and got a set of old horns for his system and couldnt be more delighted. Problem was his amp couldnt drive the speakers well and the minute changes the caps were making on an efficient setup were completely swamped out under load by his speakers. Either that or his speaker didnt have the high end extension to reproduce the change he was making, never made it through the crossover, but more likely was the first scenario. You never know what your customer's circumstances are. Even if you can measure all the valid proof in the world, there are a million reasons and two why the average guy out there does not hear your product as an upgrade or change from their current thing and using science to prove something to that guy, in his world only makes you suspect. There are no points for being "right" because the bottom line is that if end user's cant hear the change, there is no change and thats the end of the discussion. All you can say then is ok, cool, thanks for listening. And realistically, its all you should be asking, hey, take a listen, see what ya think. Some people are more critical than others, not everyone has a playback that is equivalent, many playback systems can mask the very changes you are making. Arguing with I dont hear it guy is a waste of time. What is repugnant is when I dont hear it guy tells you you are a fool for hearing it regardless of the fact that %100 of the people that have heard it on I hear it guy's system heard it too. It's just a silly, silly, silly thing to debate. Just go listen for yourselves if you are curious, it is so not that much effort. And you dont need to build devices or do double blind tests or anything else that makes for good television. Go buy 25 caps. Record 25 clips. Label the clips in your computer 1-25. Write down some where what caps were used in 1-25. Turn off the session and forget about it for a month. Then come back to it, play 1-25 and see which ones you like the best. Then go find your piece of paper and stick that cap in your guitar. Or if you dont hear a difference just pick any cap and put it in your guitar. You can take a simple LC filter, hook it up to an AP and watch the curves change. This is not voodoo. At the end of the day, if you never really leave your hometown for your entire life, it just doesnt matter if the world is flat or not. Yeah, science guy might be "right" but REALLY, what impact does it have. If you are happy with your guitar sound move along. But this is a truly silly thing to debate because for every single person you might sit down and show change for, there is another guy out there that cant find that change in his monitoring and for that guy, there is no difference. Sometimes its just like putting high performance tires on a 1987 ford taurus. When THAT guy gets out of his POS and says "this high performance stuff is nonsense, these tires didnt make my car go faster or handle better this is snake oil, I want my money back" what do you say? Sir, racing is measures in the hundredth of a second?