i have my m-audio revolution connected to a rotel surround amp via spdif. i'd like to play 5.1 ac3s. this is only possible if i send the ac3 stream to the amp and let the amp decode it.

is such a feature planned ?

No.

Any change in this policy? ac3 files are massively available. Too bad i have to keep on using programs like WinDVD, and miss a lot of the fun that's going on with Foobar...

The player's architecture does not allow for ac3 passthrough, and this isn't likely to change in the future. The only way to make surround playback through an s/pdif connection possible in fb2k is to make an output plugin that will do on-the-fly encoding into ac3 or dts. However, this isn't really a good idea because of the quality loss during transcoding.

The bottom line is that you should use an analogue connection or switch to a different player.