Or you could get a regular old power inverter. Just make sure its rated to support how many watts your system is supposed to draw. Compare the rating on your AC adapter to the rating of the power inverter. The disadvantage is that you have to bring your regular AC adapter along, as you plug that into the power inverter. The advantage is that it is universal (as you plug your original device's power cord into it) and you can easily find models that also plug into an airplane's port.