Maximum safe charging amps?

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http://forum.xda-developers.com – SO I am thinking of building my own charger for the Nexus 10 (for personal use only, not to sell). I am thinking of using a 5v PSU that puts out 6 amps (30 watts). I would be wiring the USB cable into the outputs of the PSU for connection to the tablet. Does anyone know if this would be safe to do for charging? I know the USB charger has a max amperage of 2A, and that is what the official spec says. But there are rumors of a pogo pin charger that will charge much faster, so higher *should* be safe enough to do for charging through USB right? (HowTos)