Newer B&K amps sound quite a bit brighter, harder and more sterile than their older counterparts to me. Rotel gear is also somewhat bright, but may be slightly smoother overall.
Having said that, you should have any electronic component that you bring home for audition on for at least 3 days straight. If at all possible, music should be running through the system 24/7 before doing "serious listening". When running the system during this time, low volume is better than no volume and no volume with the power on is better than no power at all.
Not only are we trying to establish thermal stability, but we are trying to pass signal through all of the components that will normally see such operation. Granted, the compononents might not be getting the work-out that they would during normal use and at higher volumes, but something is better than nothing.
If you don't like the sound of what you hear after 72 hours of continuous playing, you probably never will. Things can change after that, but with electronics, you're about 90% of the way there after this period of time / operation. If that last 10% that settles in over time makes or breaks your decision, you're walking a very fine line.
Speakers will continue to alter operation for quite a period of time, especially if you listen at low levels. I have purchased used speakers that were over a dozen years old that still weren't broken in. Throttling the power to them on a sustained basis made a DRASTIC difference in low frequency output. This was because the suspension on the woofers was never stressed and was still "tight" due to never having to make long excursions. Pumping more power through them / playing music that had "basso profundo" made a huge difference after several days. Speakers that were recently re-foamed may also go through a similar "break-in" period all over again. It is not quite as severe or noticeable as with a brand new speaker, but it does occur. Sean
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