I have jsut started making my own dvd-movies and could help looking into
surround encoding. And I realized that I dont' have a mixer nor any synth
capabable of surround mixing. But my A100 could be expanded with VCAs, LFOs
and some logicmodules and panners to make it into the DVD age! Has anybody
tried this, what modules and setup do you use

The beauty of modularity - to expand into future formats at will!