There are other reasons for wall warts: external power supplies make it easier to meet FCC emissions standards. I'm of the fewer pieces the better school, so prefer an internal adapter. Of course, since the stuff is converted to DC anyway, a DC input would make sense if it were standardized. But everyone uses a proprietary adapter with its own voltage and polarity. I know you can get multi-voltage/polarity adapters from Radio Shack, but they still don't work on everything. My Karma uses an external power supply with a five-pin connector.