Does burn-in exist on some or all solid state components? Beats me. Intellectually, I tend to side with the technical arguments that suggest that it is unlikely (unlike components like speakers, where mechanical parts can experience a physical "breaking in," burn in of solid state components is less explicable). On the other hand, I have heard and read a significant number of reports of people experiencing "burn-in" type changes in equipment and as noted above I could have sworn I heard a subtle sonic evolution with the blue-day 950 that I did not encounter with earlier designs (although one could argue that this was due to my ears adjusting to the design changes). In the end, I think perhaps the best approach might be the following: give new gear that seems a bit "off" time to settle in to the system, if only to give yourself time to finesse settings such as bass management - setting changes that can significantly alter a piece of equipment's behavior (as experienced above by SirAnthony).