@ Steven, I've been playing around with the brightness value and came to pretty much the same conclusion. The 30% reduction works great with lighter backgrounds but really sux on darker ones, and the majority of artist pics seem to have darker backgrounds.
I still think about a 10% drop in brightness value works across the full range of backgrounds in reducing the "sherbert lolly" look of the visualiser colours, but I will be content with how it is now if the "fizz effect" doesn't work out.