Hi

I have a small portable speaker, designed for taking input from
smartphones and the like, that I want to use to feed my electric guitar
through.

If I plug the guitar in, sounds does come through but it's not loud
enough. I've googled around for simple preamp circuits, and there are
many out there, however they all seem to be 9V.

I'd like to house the preamp in the speaker itself (there should be
enough space) and drive the preamp from it's batteries, which are 4.5V.

Pushing my luck here but does anyone have or know of a 4.5V guitar
preamp circuit or know whether it's likely to be feasible?

Thanks
Bigus