PSP Mix Sound 2.0 is a Homebrew application that will let PSP users mix 2 different MP3 file
on their PSP with ease. This Homebrew application known as PSP Mix Sound 2.0 has some
pretty cool features like adjusting the volume on either MP3 files playing within this homebrew application.

Quote:Improvements:
Improved GUI.
Modified functions Sound Enhancement.
Modified buttons, to facilitate the use of the application.
Added 5 icons for each sound: Rewind, fast forward, + Sound – Sound and no sound.
Improved 3D presentation.
Deleted message (Posted by Jorge_97).
Indicating deleted text and the second volume, replacing them with rods.

In the browser:

D-Pad: Navigate through the folders / files.
X: Select an MP3 sound as sound 1.
Square: Select an MP3 sound as sound 2.
Circle: Back to view the presentation.
In the application:

D-Pad: Move the cursor.
X: Activate.
Circle: Back to the browser.
Triangle: Play two songs at once.

DOWNLOAD
PSP Mix Sound 2.0

Source
Original Source