What are we listening for during break in?

Timrhu, it depends... :)
But seriously, I think when you insert brand new cables or components into your system, letting it play without actually listenning to it for a first 75 hours or so may be a good idea. Otherwise, you may jump to conclusions too early. Furthermore, some cables require warm up time after the break in. I auditioned AQ Jaguar interconnects once and found the needed about 45 minutes to open up every time I started playing my system. May be it's the DBS system that's causing it, but whatever it was, that was the case. Also, changing caps in the components, when the caps are brand new they have this plastic sound to them. 100 hours or so cures the problem.

Audphile1, I checked your system and don't doubt your hearing abilities. How can you not listen to our system for three full days while waiting for the cables to burn in? I can't remember the last time I went more than two days without listening to at least a half a cd.
I have come to the conclusion, after this thread and many others like it, I simply don't listen as critically as some who post here. When I read threads by listners who change power cables to their cd player and the system opens up with more defined bass, better imaging and/or more detailed highs I honestly wonder what they are hearing. That's where the question for this post came from. I do appreciate your thoughtful answer and the fact that you hear these sonic phenomenon.

Tim

thank you Tim. In regards to power cords. I found some power cords work better with digital and some work better with pre-amps and amps, but I can't say the difference between power cords was as big as changing Monster M550i interconnects to Acoustic Zen Silver and Matrix refernce. One story comes to mind(about component break in). A buddy of mine had his McCormack DNA-125 amplifier revised by Steve McCormack(Silver revision plus Plitron transformer). It is a very good amp in its stock form(I have one and enjoy it a lot). So, he recieved his amp after the revision has been completed, I come over, the amp sounds like a $200 Sony receiver. My friend's pissed, we're both wondering what the hell's going on. We decide that he'll leave the amp on, playing softly for 3 days. He and I haven't been listenning to this amp for three days. I come back in three days and holy smokes!!!! This amplifier sounds amazing!!! Did my ears get used to the sound? No way. I haven't been listenning to it for three days. What happened was the caps and wiring and all the other magic stuff that Steve did had finally settled and the amp is now sounding amazing. Just an example of electrical component break in. It's certainly not BS.

Audphile...

You ought to hear the other SMC mods... and as much as I don't believe in cable break-in, it did take a while for my SMC mods to show their stuff.

Bgrazman, I can imagine. I plan on sending my DNA-125 to Steve for some upgrades soon. With my speakers, the Plitron transformer, I think, is a must.