Exactly, as grizzly said: basic, just not cheap junk.
I went with a small lightweight one at the end of a cord. It has zero hum, fits easily anywhere, i.e. right behind my turntable. I plug my 100v turntable into it, and plug it into the wall outlet several feet away.
My biggest concern is forgetting the TT is 100 v and forgetting the transformer, which is why mine is just behind the TT where I can see/be reminded of it.
IF you think, I'm gonna get a bigger one just to be sure, then think about it's weight and location, the bigger the more unnecessary heat, and ...
i don't know, is there more hum potential of larger ones?