You can check the ID.
For example:
add_action( 'wpsp_before_content', 'tu_add_before_wpsp_content' );
function tu_add_before_wpsp_content( $settings ) {
if ( is_front_page() && 123 === $settings['list_id'] ) {
echo do_shortcode("[audio mp3]");
}
}
In that example, 123 is the ID of the WPSP list.
