Jeff, good point. I'd forgotten about that minor detail.
That said we've read postings from a Kobo employee which state that the device will charge from a regular 0.5 amp It's just that the indicator light won't go on and, obviously, it'll take eight hours to charge instead of two. Which basically means that if it's plugged in while you are using it it will only keep the battery roughly at the level it current is at.
BTW I keep meaning to test charging of the Vox from a laptop port. I'll do my best to remember to do that today.