Dual audio outputs via USB and PCI

STUX linux Live CD has permitted the use of USB audio and PCI audio simultaneously.

USB audio seems to be provided by the use of optical interface device SIIG USBSoundwave optical5.1 with a stereo output port and optical surround sound port (Optical).

The writer is interested in a sidelight to this subject.

KDE has provided in some versions the optional USB Audio mixer. As of this writing, I have no inkling as to how to implement this option.

I entertain any and all posts on the subject.