On PC, the Wwise Sound Engine
does all the voice mixing in software, with our own custom code, and only
outputs a single stereo or 5.1 channel voice to DirectSound. It is therefore
highly unlikely that using some specific sound hardware would change the
relative volume of voices. It is possible, however, that the soundcard's
drivers do some post-processing on the audio that would change the way it sounds
(for instance, virtual surround enhancements).
Hardware-related issues on PC
are in fact pretty much limited to stuttering when the default voice output
buffer size is not large enough for some soundcards (this is configurable
through the platform-specific initialization parameters of the Sound Engine).
