blueranger,
Do any of the nasayers believe in equipment break in? Tube break in? Speaker break in?
To be clear: I'm not a "naysayer" in the sense I claim cable burn in doesn't happen. I've just found the arguments I encounter FOR it aren't very convincing. As well, I've never heard any equipment I've ever bought, cables or otherwise, "burn in." Doesn't mean it doesn't happen.
As for burn-in of tubes: I don't know. (I actually have a brand new pair of tubes I'm going to be putting in my CJ pre-amp. Unfortunately, even in as a casual test of burned in vs non-burned in tubes, it wouldn't work in my situation. The reason I'm replacing my tubes in the first place is that the old ones have become more noisy, hiss coming through my speakers, so there ought to be an obvious change when I put in the new ones. I hope there is!)
Burn in of speakers: Much more plausible than what's been offered for cables. But there seems very, very little hard data on the subject. And analysis by the people who have tried measuring speaker burn in - e.g. drivers burning in - generally seem to point out if it happens the audible results would tend to be very subtle, and that any likely audible difference in break in happens fairly quickly, vs the hundreds of hours one often hears about in high end audio.