I reluctantly put a 20A on it and forgot to upgrade to a 30A and it's been fine. Defiitely no lower than a 20A though would I recommend. BTW, I got a little crazy and through a 30A Radio Shack inline noise suppressor on the main hot going into the Keypower for more noise control. My setup is super quiet.
PII 266, 512 MB RAM, 10 Gig, 36x CD-ROM, 16x DVD, DeLorme GPS, 5.6" LCD Screen, Dschmidt power controller, Keypower ATX DC-DC Supply, PowerAmp Macro controller, Dauphin mini-Kbd.
Sony Head Unit, Sony Unilink input selector, rear deck Kenwood 6x9's, stock door spkrs... All in my '96 Civic, of course :}