Doug C:

For a start I got the chords wrong for Kid on the Mountain (purple-brown-yellow-brown).

When you move the capo up (on a bouzouki in my case), the colours change, mainly to yellowy-brown hues. What key is this? If it is A as I think it may be, then that makes sense - my music theory is a tad sparse.

Interestingly, I play Connaught Man's Rambles with and without a capo, and the Bm seems to change hues of blue. Lighter edging toward turquoise with the capo on the first fret, a deeper blue uncapo'd.

I can recognise some keys by their colours - D major is browny-red (but not uniform - the red is brighter in places, rather like a Rothko).

Ebbie asked if the color intrudes on the experience or enhances it - to me its an enhancement, adding to the experience of the music.