Hi, I'm really here just to ask a very basic question. I have a rechargeable Bose speaker which takes a 17-20V, 1A current from its power supply to charge its battery(ies). However, I lost or otherwise cannot find the transformer. So like most, I have more than a dozen orphaned black bricks floating around the house. Assuming the correct plug, they range from 5V and 600mA to 12V and 3A. Basically I'm down to 2 choices, both 12V (less than what the speaker takes) but one is 1A one is 3A. Basically my question is would either 12 V work but just take longer? And would the 3A be dangerous or with the slightly lower voltage be OK? Please excuse my profound ignorance. I never read my father's electrical engineering book he had on his shelf. And TIA.