Hi,
Beolink 1000 is ideal, i wouldn't recommend AV terminal.
Regarding which Beolink, i would use the one with the MENU and LIGHT button.
Depending on which MX4000 you have, a Beo4 might also be very suitable or even be more suitable,
as this would also give you more flexibility if you should use other B&O products as well.
Which type-numer is your MX 4000 ? (4 digits)