Currently, the Output Format DSP is fixed at the top of the DSP Studio.
This means that if you are a headphone user, where everything needs to be mixed down to 2 channels, dowmixing is the first step that happens to the audio.
This prevents the use of any VST Plugins that do advanced signal processing to transform a multichannel source into a binaural headphone mix for 3D positional audio.
I don't know what the solution for this is though, whether it would "simply" mean allowing Output Format to be somewhere on the plugin list other than the top, or separating the channel mixing options from the resampling ones.
This option could also potentially pave the way for AstoundSound support in MC. (either licensed, or through a plugin)
And - on a related note - it would be really nice if you supported Dolby Headphone via
DOLBYHPH.DLL, similar to the way that DTS-HD Decoding is handled via
dtsdecoderdll.dll.
It's far from the best 3D audio support for headphone use, but it's bundled with a lot of software, and it does work to give you much more directional audio rather than the basic panning effects we are stuck with just now.