Hi there: just to make matters worse I bought the SF-2 from a friend of mine in Portugal so the power supply is for EU! However, don't know how this affects the voltage (I'm not that technical myself...)
I do know that a simple mains socket adapter solves the plug issue and I use this for both EU and US products I've bought, I haven't had any issues but in terms of the US products that amounts to a compressor pedal, an iPhone charger and the Mrs' hair dryer... However, as always, I would defer to the wisdom of Mica and Alembic for the final word...
;-)