I recently got a Creative Zen Vision:M 30 GB and it did not come with an AC Adaptor. Having looked on some sites, I have found that the Vision:M's charger is 5V and 2.4A. I have a charger from a Creative Zen Xtra 30GB that's rated for 5V and 1.5A. Is this charger safe to use for the Vision:M with its amperage difference?