I am wondering if all AC Adapter for USB Powered Devices are the same volts etc and can be used universally on any USB device. In this case I just bought a Emerson EM543 4.3" tablet. The company has an AC wall charger for $15. But I thought I could possibly use the AC Adaptor for USB devices that came from a cheap Asian mp4 player. Of course I can charge from the tablet to a computer. There are no specs for this from Emerson and I want to make sure i don't damage my tablet in case the adaptor is not compatible. The tablet uses a micro plug in where the mp4 player uses mini jack. The AC adaptor plug itself of course is a usb jack.