This incredibly small stereo amplifier is surprisingly powerful - able to deliver 2 x 3.7W channels into 3 ohm impedance speakers. Inside the miniature chip is a class D controller, able to run from 2.7V-5.5VDC.
This GPS antenna draws about 10mA and will give you an additional 28 dB of gain. It's got a 5 meter long cable so it will easily reach wherever you need it to. The antenna is magnetic so it will stick to the top of a car or truck (or any other steel structure).