I'm neither an electrical engineer nor a tech, so perhaps I'm not qualified to answer this, but I've dealt with plenty of electronics and I've been able plug power supplies with more voltage than required by the component and have never had an issue with it.
Perhaps someone with more knowledge will jump in, but just wanted to perhaps ease your mind a little. The only times that I've plugged something that really caused damaged, the damaged was immediate and apparent. (burning smell, spark, etc...) And the unit didn't work after that.
So, if it sounds good, I think you should be fine.
Hope this eases your mind a little. At least until someone who really knows what he's talking about chimes in.