Applying some science from another discipline might be interesting.
If orange or red fuses were described by users as adding brightness or detail, and if blue fuses were described as adding smoothness and “tubey” qualities, then this would add to the arguments of those who shout ‘placebo’ and call for double blind testing. Because sugar pills those colours cause patients to perceive these effects on their senses according to colour. On the other hand, if these effects are not reported, or are reversed, this is evidence for the ‘trust your ears’ community.
Or is the colour effect the other way around...? Ah! The double bluff!
Take a card; take any card. Don’t show me the card, show it to the audience .. look into my eyes, not around the eyes, look into the eyes...