Why risk anything? Can't a preamp burn itself in properly by itself over time, or do these "burn in devices" condition the preamp in a certain way? Personally, I have to believe that any reputable designer would have tested the prototypes after they were broken in and then made adjustments so that the production models ran properly.
If I were going to invest in anything, I would invest in a variac transformer. I'd use it to gradually condition the equipment to full voltage. Things would probably last longer too.
If I were going to invest in anything, I would invest in a variac transformer. I'd use it to gradually condition the equipment to full voltage. Things would probably last longer too.