Is it possible to convert a headphone amp into a speaker amp?

I bought a cheap replica of Apple's Universal Ipod Dock, which has a line out (includes an LM4811 amp chip). My goal is to convert the headphone amp to a decent speaker amp -- similar to the Altoids Tin Speaker (https://www.instructables.com/id/Altoids-Tin-Speaker/), but without the battery or switch. I want all of the power to go through the dock's PCB, so I'm trying to avoid as much as I can an extra power source just to power the amp.

This is part of a larger project that I've been working on for a while (and learning as I go)

I can provide pictures later on of the dock's PCB if anyone wants to take a look.