Specifically, I have an Alarm Clock iPod dock with speakers that gets its power from ac wall adapter, but is only providing 12v. Is there an adapter to go 12V to 12V that will power this?

I want to put this in my camper, but run on 12V so I dont need to be plugged into shore power or have engine/generator/inverter running. I already have inverters and a generator, but this is for when dry camping and not running the engine. I have 200 watts of solar, so I am not too worried about running down my house batteries. I would rather use a standard cigarette adapter than hard wiring it to keep it portable.

Thanks