Naw, Adrien; certainly no disaster if a mode other than all-channel stereo was set temporarily. Of course all channels don't have to be played simultaneously; selecting "none" for back surrounds and the outside speakers don't play, likewise the second inside set if side surrounds are set none.
The 508 also has a powered "Zone 2" option which would allow one of the other speaker sets to play different material with different volume settings, if wanted.
There are quite a few more or less complex and/or expensive solutions, but this simply uses the versatility built in to modern HT receivers.
