abnavraham said it best...break is only between your ears.
He is wrong, and if you are agreeing with him you are wrong as well.
This is from the manual of the Playback Designs MPD-8, which many would state is one of the better sounding DAC’s going, which concludes the designers Andreas and Bert must have pretty good ears. What is between their ears is a pretty good audio engineering brain, strong enough to determine the difference between auditory truth and false perceptions.
BREAKING IN THE MPD-8 Breaking in the MPD-8 is time consuming but well worth the effort. It would be a mistake to pre-judge the player based on what you might hear at first listen. This is what you can expect to hear at different intervals during break-in:
1. Out of the box: The DAC will have good clarity, but the highs can be recessed. Bass might appear to be a bit muddy and lacking punch. Soundstage might sound closed in.
2. 50 - 150 Hours: The sound will open up a little bit, but can still sound a bit brittle.
3. 150 - 350 Hours: Midrange will start smoothing out and clarity will increase, but highs might continue to remain recessed. At this point, there probably will not be much change in the bass. You will probably wonder how the Playback Designs converter will ever sound like others have described, but we assure you that you will start to hear substantial changes within another week of play.
4. 350 - 500 Hours: The magic will be starting. Highs will be open and airy. Midrange will appear much more full bodied and natural. Soundstage will be huge and the image presentation will start appearing very holographic. Bass will be incredibly deep and tight with texture and detail galore.
5. Over 500 Hours: The DAC will continue to change subtly over the upcoming month of usage, but you should be recognizing a very life-like and natural sound. During break-in when you do not listen to music it is best to feed an external digital audio signal into any of the digital inputs of the MPD-8.