This is what I get since upgrading to final from latest beta:
Unrecoverable playback error: KS output error: error opening device

The difference between ks and ds is "just" being able to play rips/cds without constant stuttering/freezing playback.

Wasapi doesn't work either (can't install sp1) and asio4a doesn't have output.
(Vista 32 and Realtek AC97)

So, now it's all working - both asio and ks (go figure!).

Just to clear some doubts:
I guess asio is preferable to ks (?).
Foobar reported "8 channels detected when 2 expected" - asio had all channels set to <none>; I set the first two to left and right, kept all others to <none> and added "5.1 to stereo" dsp (I use mostly headphones over stereo loudspeakers).
I now have advanced limiter, 5.1 to stereo and crossfeed dsps (in this order).
Is this setup ok, including for downmixing multichannels, or which output should I set each channel to, in asio?