Question about Channels in SDL_mixer

Hello !

I always thought that when using SDL_mixer with
Mix_OpenAudio (…, NrChannels, …) it would support
"NrChannels" of independent channels.

For example 8, 16, 32. But in mixer.c it also calls
SDL with this NrChannels. But from the docs for SDL
this means 1 - Mono, 2 - Stereo, 4 - Surround, …

But the thing i need is to have for example 8 channels,
but in the end they should be mixed to a
normal stereo speaker output.

I noticed this when also trying my game with Waveout settings
in SDL_AUDIODRIVER. I called there Mix_OpenAudio with 4 Channels
and it fails under Waveout, but works with Direct Sound.