This may very well be a tough one to answer in this forum. Have you also tried Audio Asylum?
Being a former chemist who did a fair degree of color work, I've personally gone through the pain of understanding how complex a subject color actually is. I'd probably say that though I was involved in some really high tech (military, aerospace, alternative energy, commercial, automotive) projects, color was the hardest thing I had to do, and I learned to do it by eye (as I found the best people do) as opposed to cameras, computuers, machines, colorimeters which is ironic in that high-end audio is much the same way - ear versus measurements.
But, seeming to contradict that, one must have a color specification to use as a guide in order to convey a color to another human being. Recently, while working with quite an experienced manufacturer in this business, whenever I brought up the subject of RAL colors, it was apparent he was not familiar with the topic, and instead would talk to me in terms of light, medium, blue, etc. in trying to discussing tone. My prediction is that if someone with that depth of experience had little to no understanding on the topic, it may unfortunately be a tough slog in plumbing the audiophile community for an answer.
I suggest that if you don't find someone to answer your question on these forums and it's critical to you to have the proper color, you'll need to purchase one of the RAL guides to have the best chance at a proper match. Of course, even after you pick what you feel is the right one (look at the guides in incandescent, flourescent, and sunlight - you'll be shocked at how wrong you can initially be) have a test run done to make sure it ends up as you expect before you have the target piece done. If you're going to have someone paint the unit for you, you may also want to discuss the job with them, as some outfits feel more comfortable with the Pantone color specification, in which case, it would be smart to buy that one instead.
