System synergies: Chaotic or predictable?

When speaking of system "synergies", do you consider these to be chaotic? or are they a predictable sum of the character of the components?  I'm surprised at people who think they can predict the sound of a system from their perceptions of the components (derived, in turn, from other system combinations), and even more surprised and suspicious of the 'tone control' approach to purchasing cables and amplifiers suggested by another forum member (who does happen to be a dealer). 

I think these two views are contradictory. If we think that components have 'magical' synergies beyond our ability to measure, then it seems unlikely that we also can predict how combinations of components will sound.