Theoretically any adaptor SHOULD work, provided voltage, amperage, polarity and connector size all match. Depending on the price difference, I have a slight tendency to opt for the original.
What I wonder about is, why would you want to use the SL2 at all if you are not using a laptop? Or is it just that you want to keep it hooked up and not have your laptop on sometimes?
Reading up on the subject, it seems that the SL2 thru function is now performed through the software, whereas the SL1 had it in hardware. And software means laptop on, I think.
Greetinx.