I don't know if I can offer anything other than moral support. As you well know, many audiophiles have great difficulty with judging performance by "measurements". If we bought according to "measurements", nobody would buy tube amps. People would all have Pioneer receivers with distortion measurements of .00001. No offence intended to the owners of Pioneer's fine products. It is the lack of standardization in measurement methodology which is one of the reasons for this of course. As somebody once said: "Standards are a good thing, that's why we have so many of them".
I would make further efforts to encourage them to actually try it. Do you have a guitar that you can demonstrate with if they won't try it themselves? You can maybe needle them a bit to cajole them into trying. Ask them why they trust measurements more than their own ears. Ask them why they want to be told what is better rather than seeing and hearing for themselves. Ask them why they're so closed minded...suggest that as they get older, they're becoming more like their parents! Middle age is that time in life when one's broad mind and narrow waist change places. Most guitar geeks are a bit of a rebel. These type of sarcastic comments might arouse them to their natural non-comformist state and they might try something just to be defiant. Ask them why they use crappy tube amps when solid state amps "measure" so much better.
And of course, if it does work and they try it, you'd better make sure that you have a power cord that actually does sound better.
I would make further efforts to encourage them to actually try it. Do you have a guitar that you can demonstrate with if they won't try it themselves? You can maybe needle them a bit to cajole them into trying. Ask them why they trust measurements more than their own ears. Ask them why they want to be told what is better rather than seeing and hearing for themselves. Ask them why they're so closed minded...suggest that as they get older, they're becoming more like their parents! Middle age is that time in life when one's broad mind and narrow waist change places. Most guitar geeks are a bit of a rebel. These type of sarcastic comments might arouse them to their natural non-comformist state and they might try something just to be defiant. Ask them why they use crappy tube amps when solid state amps "measure" so much better.
And of course, if it does work and they try it, you'd better make sure that you have a power cord that actually does sound better.