[mcmusicman]

Greetings all,
       I am about to place an order for a new pair of Magnepan 3.7i and have a few questions since my 1.7 were purchased used.
Are there any changes I should make immediately to fuses or attenuators or should I wait until after break in? During the break in process do I need to consider sound levels regarding the time? For instance, a certain number of hours before exceeding 60 db etc?  Is it fine to simply leave them on a long play list while I go to work at a moderate sound level and let them run 9 hours without changing volume to accelerate the break in?  Any tests I should run post delivery to make sure everything is correct? My concerns may sound silly but this will be the first time buying a set brand new and I plan on keeping these a very long time.  I would like to do this right and frankly the only dumb question is the one not asked. 

Room is 20x16 with half wall into similar overflow space.  Powered by 4B3.

[I.Greyhound Fan]

Do not change anything until they are broken in.  You can leave them on 24 hours a day to break them in.  I varied the volume and music when I broke  in my 1.6's and MMG's.  They need about 75 hours.

As far as tweeter attenuators, if you find the treble too hot you can try a Mills 1, 1.2 or 1.5 ohm resistor-

https://www.partsconnexion.com/mills-mra-12-resistors.html

Or a Duelund resistor-

https://www.partsconnexion.com/duelund-cast-graphite-resistors-carbon-w-silver-leads.html

I found the Mills to give a warmer sound.

As far as fuses, you can play around with them.  I found a high end fuse to actually make the sound worse but as usual, YMMV.