If your 15W amp takes 12VDC, you have to compare how much it needs vs how much you've got (and if it's batteries - for how long...)
If it's an invertor, it better be a good one or it'll probably be noisy. And it still comes back to "how much 12V you got"? (in Ah).
__________________Club Hartke - #337 | Steinberger Synapse Clubb - #8 | Fretless - #886 | Darkglass - #77This old man, he plays 6...