Ah my first terminology problem! I was referring to an unpowered hub as a 'splitter' not one going the other way.
I could possibly see that using two ports to power the device would provide more 'juice' but that doesn't explain why it will recognise it fom a single port when passed through an unpowered hub and not when connected directly (if anything that would split the power to 4 different devices thus reducing it wouldn't it?)
