Need Help with Voltage for Integrated

I recently acquired an Arcam FMJ 18 (nice little unit, BTW), plugged it into my standard (120/240v) power outlet and began using it without problem. Subsequently, I saw printing  on the back of the unit that indicated 220/240v. There is not (contrary to the manual) a switchable power button on the back. My working hypothesis is that either (a) the printing is erroneous and the unit is 120v, or (b) I'm using the wrong power supply and will fry the unit. FWIW, the previous owner, who was something of a stroke, told me that he had used the unit with standard 120v power with no issue. Should I be concerned here?
Changing the fuse value will not change the voltage capability of the unit.

No one said otherwise.
The issue is that the unit has multiple internal locations for the fuse, depending on wall voltage. Each location probably requires a different amperage.
Erik, you're reading skills strike again! lol.  If you scroll up to reubent's comment above, the first thing he says is this:

Per the downloadable users manual Version at the Arcam site,the voltage is changeable via a fuse internal to the amp.