I'm very happy with my MH750 Magnum biwire but no experience with the 770. Here's some comments on MIT from an archived thread:
http://audiogo5.iserver.net/cgi-bin/fr.pl?fcabl&994622494&read&3&4&Bob_bundus&53wNWQ6xyzUcg
http://audiogo5.iserver.net/cgi-bin/fr.pl?fcabl&994622494&read&3&4&Bob_bundus&53wNWQ6xyzUcg