Almost all of the speakers that I have seen are 9v, 300mAh. It should say on the speakers, by the adapter plug-in. But I have a pair that doesn't, so maybe yours don't either. Also, it would help to know if the plug is tip positive or tip negative. Midiland's website (
http://www.midiland.com ) doesn't have an online manual for that model, but they do have an email address for tech support, so I guess if you don't find out anywhere else, you can send them an email.