Ah ha! I don't consider that period burn-in.The cable and drivers collectively sweetened, if you would. Of course, this is my view. On a side note, over the years I've heard many pieces of gear - some pieces over a very long time and their replacements due to something being sold or returned for repair. I have heard amps, decks, speakers and other goodies filled with electronics sometimes change with age. Some seem to think this is a stretch, that capacitors, resistors, wiring and such will not age and possibly affect the presentation. Um, I'm so happy for that camp over there. Yes, many things can affect what we hear, what we think we hear and what we WANT to hear.
Besides being a long time enthusiast of music and gear, I worked in Home Audio (Retail) and Car Audio (QA - manufacturing).