How to combine multiple audio files of different formats together?

[mainrs]

Basically, I have two audio files. One contains the instruments of a song and another the vocals. I need to create a single output stream that combines them both.

The issue is that no Java library I found is able to playback two files in sync. So my idea was to use Jave2 to first create a combined audio stream and send that to the output device.

I don't need the result to be saved to a file. If possible, I'd like to send the resulting stream.

Bonus points if I can adjust the volume of each audio file inside the stream during playback somehow.

I looked into the documentation, but it wasnt clear to me how to do this.