Power adapter roulette, How to beat the odds?

All help is appreciated, but let me begin by saying I know there may be risk involved with using other than the supplied power supply, however...

...Old junk without power adapters is almost as bad as old junk that got fried using the wrong power adapter. Electrical power is highly mysterious to most of us. This mystery is only deepened when manufacturers of devices fail to list the specs of there external power source requirements. Sometimes they give you partial information, such as "6V". Sometimes not even that.

The situation: I have an old external usb 1 into 4 hub. I don't know how they are now, but in those days they either had batteries inside them (seeming cheesy to me), or they had a power supply. Obviously we are not talking about a great deal of power, but who wants to change batteries? The unit is made by D-Link. I looked it up on the web, but could not find out anything beyond just the voltage.

General question #1 - if a device normally uses a certain voltage adapter that is rated 300mA of current, would that mean any adapter with the same plug and voltage rated 300mA of above work. It would be capable of supplying more current, but that would only be if something was drawing more current, correct? (it would seem to me that too low a rating might mean that not enough power to run the device - Possibly damaging it in the process, though something with no moving parts might be ok?)

General question #2 - anyone familiar with the term "switching adapter"


-HandsOff