This is a hardware question. I have a project that uses sound effects. One sound effect is a constant background sound, and then when the user interacts with the buttons, there will be sound effects that play separately. I need on DFplayer to play the constant on sound, and one to play the button sounds.

My question is, how best to amplify this and run it to the same speaker set? I dont want to use two sets of speakers for the project, rather have both players go to the same speakers through a 1/8 in TRS jack. Looking for recommendations on how to do this.

This kind of usage should not work. There is a power amplifier on DFplayer, unless you can achieve that when one player outputs a signal, the other player is powered off. I think you can store the button sound as a separate file in the SD card, and play the button sound first and then the corresponding background sound during interaction