Hi Basti,
You can add this code to your bp-custom.php file:
add_action ('bp_before_directory_members_content', 'move_filters', 5);
function move_filters ()
{
remove_action ('bp_before_directory_members_content', 'bps_add_filters');
add_action ('bp_before_directory_members_tabs', 'bps_add_filters', 20);
}