Re: AW: 3551 bugs This is probably related to the routing bug (of stereo audio) with Master Mixer on Vista/7. (i.e. in the default DSP config, Surrounder (basically) expects that stereo audio will come from FxBus 0/1). That is expected behavior. The only multichannel outputs are Wave 0/1 / Master Mixer (and equivalent WaveHQ device). (The SPDIF/AC3 output is intended for stereo PCM or AC3 (utilizing the sound card's SPDIF output (assuming the kX AC3 decoder is not enabled))). As indicated in a previous post, WaveHQ requires a custom DSP config in order to utilize certain DSP plugins (like Surrounder). i.e. In order to avoid resampling, etc, WaveHQ bypasses the DSP (thus no DSP effects). However, WaveHQ can be routed to the DSP via P16v plugin (and 26/96 router), but (IIRC) the default config only routes P16v to reverb/chorus... for Surrounder to work with WaveHQ, it (P16v plugin) would need to be connected to Surrounder with the appropriate channels connected to the appropriate inputs on Surrounder, etc. (along with the appropriate settings in 24/96 router).