Since Hans added multi-channel support to ST, it is now a usable solution for watching movies.
I know the surround sound support is still being worked on so I expected a heap of problems.
To my surprise it works perfectly out of the box.
-Install ffdshow and set it as preferred codec for everything it supports. Easiest way to do this is to use the k-lite codec pack, it has an option for this in the setup.
-Install Winamp and the DSP version of ST.
-Open ffdshow audio config and enable the "Winamp 2" plugin. Then select ST in the list of DSP plugins. Also enable "allow multichannel audio". Disable the volume plugin in ffdshow since ST will do all normalisation.
And that is all that is needed. Whatever media player you prefer, if it uses the standard system codecs it will use ffdshow and run its sound through ST. (I use MPC-HC)
Even the audio-delay from ST is corrected by ffdshow so no problems with lip-sync.
On the video side, optionally you can install SVP to do frame interpolation via ffdshow. (aswell as a bunch of other fancy filters)
My AV receiver has now been reduced to a glorified DAC. Thank you Hans.