I bought mine in Best buy in Florida. before I moved to Europe, before that I traveled with it to EU. Straight out of the box in the USA without a issue will work on 220V. I have 2 of them. I can only speak for the Ultra
That's great then. The wall cube must be 110-220v compatible. Of course, the US version will have the wrong plug, so an adapter is needed. But no converter necessary.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.