I am not sure about the fuse rating for the airmotiv 4 because I have the airmotv 5s. If you are not sure email emotiva and inquire about the fuse size for the airmotiv 4. They were very helpful when I inquired about the fuse size on all the emotiva powered speakers that I have owned. I have had three the airmotiv 5, the airmotiv 6(sold off replaced by the stealth 8) and the stealth 8.Each speaker has one fuse in it. The fuse is easily accessed from the rear panel. They are directly under the the iec power inlet. If you look there is a symbol of a fuse on the removable fuse holder. There is a small slot located just under the iec power inlet. Just place the blade from a small screwdriver in the slot and pry the fuse holder out do not do it forcefully just a little pry and the fuse holder will pop out. The fuse are directional so put the fuse in the holder with the hifi tuning fuse name on the bottom and reading left to right. Just slide trhe fuse holder back into the speaker and it will snap back in place. If it does not flip the fuse holder over and try it again.
These type of fuse holder are becoming more common on equipment. They make changing fuses much easier and makes it unnecessary to open up the unit.