I’ve had conversations with dCS folks who say that the Bartok Apex needs 100 hours of run time with small changes occurring during the next 100 hours or so. I know a number of equipment designers who are unsurprised by this. For example, two preamp designers I speak with regularly (Certified Master Engineers with all the degrees) select their capacitors by the way they “sound” in their circuits and then compare and track the run-in time. Only when they sound “right” after run in do these two engineer/designers select them for their final products. I tend to give credence to qualified opinions like that.
My ears tell me a similar story. It took 200 hours for my upgraded Bartok Apex to fully stabilize in performance and exhibit the signature dCS sound qualities I’d become accustomed to with the older unit. Eventually, the Apex’d unit produced all instruments in a timbre-ally accurate and organic way. No need to flame over this. I’m just another knucklehead with an opinion and his own set of experiences.