I challenge anyone to determine the real break in time for fuses or capacitors or any electronic component for one reason: How can you keep track of the sound closely enough to know when the sound is no longer improving? Do folks stand by and wait patiently for the fuse to break in, monitoring the performance a little bit every day and do nothing else? Then repeat the process for the next fuse? The Duelund capacitors are rumored to take 500 hours or longer to break in and I'm even not sure if that means completely broken in or not. The system and environment cannot be controlled well enough to conduct such an experiment. This is especially true for most audiophiles who are continually moving thing around, changing out one component or another, changing cables, trying various tweaks, changing fuses, changing the direction of fuses, adding room treatment, removing room treatment, etc. There are too many variables. Has anyone used the XLO Test CD burn in track to break in fuses? That would be a little more effective than simply playing music and it can be played non-stop. And if you’re looking to squeeze some more juice out of the tangerine why not cryo the fuse?