The Jamstack 2 has a built-in receiver that uses SKAA technology which only SKAA transmitters are compatible with. Of course the Jamstack 2 can amplify whatever you put into the 1/4" jack so if you already own an external receiver/transmitter pair that will work just fine.
For a list of compatible products, please review this list on the SKAA website: https://skaa.com/hear/
Please email info@jamstack.io if you have any questions about this.