Do not worry about the milliamp. As long as you use an adapter thats the correct voltage (you stated 12 volts), the end connector fits into the speakers and the polarity is the same, then you wont have any trouble.
I have a pair of boston acoustics computer speakers BA265. One has a burnt resistor no sound. I...
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I have a pair of boston acoustics computer speakers BA265. One has a burnt resistor no sound. I haven't been able to reach their technical support for a schematic.