Actually looking at the Decibel webpage … you can run the Space at 12V DC with a "2.5mm Center Positive Cable "

From the Decibel website it links to this Amazon page… http://www.amazon.com/gp/product/B00IRJ619U

I know I said 9V DC 500mA … but they can run at 12V DC @ 400mA … (that is what the PowerFactor runs them at 😉