Well, but if you needed Dialog to setup the stereo system then it doesn't count, because without a Dialog you could not set it up like that, unless you have a friend from whom you could borrow one to setup/re-setup your system whenever something goes wrong... 
However, there is a way it might work... If you use different optical cables connected to the two phantom, and then feed them only the left channel on one and the right channel to the other one, it might work, even without Dialog. However, I don't know if you would be able to control the sound over Spark... I have a professional sound card where I could re-route the different channels, but unfortunately it only has one SPDIF output, so, I cannot test it...
However, there is a way it might work... If you use different optical cables connected to the two phantom, and then feed them only the left channel on one and the right channel to the other one, it might work, even without Dialog. However, I don't know if you would be able to control the sound over Spark... I have a professional sound card where I could re-route the different channels, but unfortunately it only has one SPDIF output, so, I cannot test it...
