I had a quick look around, the only DC PSU I can find that comes anywhere near that is the one I use with my Empeg at 1.2A. Will this make a big difference ?
It may be just me misreading, but you're not thinking of connecting your empeg PSU to it are you??

The empeg runs at 12 volts & from the other post your Riot runs at 5 volts.... surely NOT GOOD

Cheers, Sim