Hmm. I've just done a bit of Googling and for some bizarre reason, 10v universal power supplies seem to be rare. Ones that support 9v and 12v seem to be all over the place but whether you want to risk one is up to you. I think it will come down to how good the voltage regulator in the SNES is...?|
Do not use a travel adapter! They don't change the voltage at all, they literally just adapt the shape of the plug so it will fit - the reason the wife's hairdryer works in the US is because it is already designed to work on 110v. I suspect you may actually be basing this on a European holiday anyway and their mains power is the same as ours, that's why Euro adapters are so readily used.
A travel adapter that changes the voltage is a step-down converter.
Speaking of which the step-down converter you found from Amazon is the most economical solution now as far as I can see, since the only 10v universal PSU I can find is a bit pricey (http://goo.gl/DNHL6). Sorry if I confused matters the other day! BTW to answer your question about the wattage, 45W should be more than enough to power a SNES, since based on my maths the SNES should only use 8.5W (10V x 0.85A = 8.5W). The figure goes up and down based on how hard the SNES is working though but I doubt it would spike to 45W.
If anyone else wants to verify that none of this has come out of my arse that would be lovely!
21 consoles, 5 handhelds, 2 PCs, 1 Mac and about 700 games from the past 30 years. Every major manufacturer and developer represented. Still a fanboy for disagreeing with you.