I have been a guitar player for 30+ years and into audio since the 1970's. Yes, I can still hear the subtle differences! I have even had my hearing tested over the years. I upgraded the power cord for my Marshall JCM900 50 watt reverb top, running through a Mesa 4 x 12 slant cabinet (guitar lingo) and I can hear the difference in dynamics, sustain, and "chunk" in the sound. That is true whether I am playing my American Reissue '62 Stratocaster, Buck Owens Tele, 1989 White Les Paul Custom, or Paul Reed Smith Custom 24. Many companies are making "high end" guitar to amp cables now, including Monster and Tara Labs and DiMarzio. To me the differences are the same as audio applications in terms of improved frequency response and harmonic content. Show them my reply and they can tell by the gear that I take the guitar stuff seriously. You might need to point them in the right direction as to what to listen for. One thing about most guitar players, whether the guitar sound is distorted or not, they know when a type of guitar's sound is being accurately captured on a recording. Good luck!