Hi Søren,
If you have the speakers connected to the BM7000 then you will lose out on the surround sound.
If you connect them to the BV7 and have both in option one, and use AV then your Beolink 7000 will still be of use. It will give full display when you press Radio,AV,Radio or CD, AV, CD.
When you watch, for example Satellite, press DTV, AV, DTV then the Beolink 7000 will read Sat but the volume number will just correspond to whatever passives you have plugged into the BM7000.
In my opinion, it's worth the effort of using the AV button and still being able to enjoy your Beolink7000
Andy T.