REL Sub Bass Systems have a AC mains fuse located in the IEC receptacle where the power cord is plugged in. The fuses are located in a drawer that must be pulled out after the power cord is removed.
This drawer can be opened with a small flat blade screwdriver placed in the notch above the drawer.
There are two 5mm X 20mm 250VAC fuses in the drawer. The one farthest inside is the active fuse, and the one in the square holder is a spare. Fuse ampere ratings for input voltage of your region are printed on the outside of the amp panel next to the fuse drawer.
So, I am not saying Rel says that’s the way to change voltage...there may also be something internal besides the fuse that is different...I noted in my original post that on my Bel Canto I only had to change the fuse and wondered if maybe this is the same.crn3371, I did write to them and they gave me the responsible answer of buying one in 220 and then when I go back to the US, sending it to California to get the amp swapped for a 110. Seems like a LOT of hassle if I could do it myself.