You might find this thread I started in AudioAsylum interesting:
http://db.audioasylum.com/mhtml/m.html?forum=digital&n=172907&highlight=rip+dull&search_url=%2Fcgi%2Fsearch.mpl%3FForumSelect%3DSelected%26searchtext%3Dcbs%2B6sn7gtb%26SelectForumtubes%3Dtubes
http://db.audioasylum.com/mhtml/m.html?forum=digital&n=172907&highlight=rip+dull&search_url=%2Fcgi%2Fsearch.mpl%3FForumSelect%3DSelected%26searchtext%3Dcbs%2B6sn7gtb%26SelectForumtubes%3Dtubes