hi ukandrewf.
It's an easy hack.
line 33 of viewcat.php
// Orders
$myalbum_orders = array(
"titleA" => array( "title ASC" , _ALBM_TITLEATOZ ) ,
"dateA" => array( "date ASC" , _ALBM_DATEOLD ) ,
"hitsA" => array( "hits ASC" , _ALBM_POPULARITYLTOM ) ,
"ratingA" => array( "rating ASC" , _ALBM_RATINGLTOH ) ,
"titleD" => array( "title DESC" , _ALBM_TITLEZTOA ) ,
"dateD" => array( "date DESC" , _ALBM_DATENEW ) ,
"hitsD" => array( "hits DESC" , _ALBM_POPULARITYMTOL ) ,
"ratingD" => array( "rating DESC" , _ALBM_RATINGHTOL ) ,
) ;
if( isset( $_GET['orderby'] ) && isset( $myalbum_orders[ $_GET['orderby'] ] ) ) $orderby = $_GET['orderby'] ;
else $orderby = 'titleA' 'hitsD' ;