custom post type archive template per custom taxonomy term

I solved it.

SOLUTION:

<?php 
if ( has_term( 'downloads', 'listen', $post->ID ) ) {
    get_template_part( 'templates/content-downloads-vergriffener-baende' ); 
} 
elseif ( has_term( 'untersuchungen', 'listen', $post->ID ) ) { 
    get_template_part( 'templates/content-untersuchungen' ); 
} 
elseif ( has_term( 'studien-materialien', 'listen', $post->ID ) ) { 
    get_template_part( 'templates/content-studien-materialien' ); 
} 
elseif ( has_term( 'sonderbaende-kataloge', 'listen', $post->ID ) ) { 
    get_template_part( 'templates/content-sonderbaende-kataloge' ); 
}
?>

This post: http://wpquestions.com/question/show/id/2038 has been greatly helpful in the process.