Nice tip, Yek !
It has to be with psico-acoustics, not sound itself. The volume is a variable that has a major rule in our ear's perception of sound. As you get louder, your ears (your ear sense, in your brain, not your ears themselves) get more sensible to bass and treble.
That's why lot of times you come with a beautiful tone at bedroom level that sounds like crap when going to a full-volume FOH, lot of highs and lows. I found myself lot of times enjoying my tone through my monitors and when I go down wearing my guitar and my wireless to check how it sounds through PA it's kind of shit, 'U' eq.
Different volume, different perception of tone even if the rest of variables are the same.
I'll try your solution Yek, and will tell you how it goes