You could go for the Palmer acoustic pre amp but if you don't have a power amp and speaker to connect it to you would only hear through the headphones what is being picked up by the acoustic guitar pickup, and the onboard speaker emulation from the pre amp. There's nothing wrong with doing it that way but I think you would find a better tone and long time use from using and acoustic amplifier with and aux in, you can always then at a later date add the Palmer pre amp to the rig for more flexibility if you want to.

The Laney LA30D would be a good choice and it also has a headphone input if you are needing that.

https://www.laney.co.uk/products/la-series-la30d-solid-state-combo