Creative Soundblaster PCI / SB 128 / Ensoniq AudioPCI
are apparently closely related. These cards apparently have 4-channel analog output, according to Thomas
       Sailer:

"...mine is rather old. The cards have an analog multiplexer on board (4051 I think, or similar), and in 4 channel
          out mode, the line in jack is switched to become the second line out jack for the other 4 channels. 
          If you look at the codec datasheet (akm4531, www.akm.com), you'll see that it has 2 2channel DAC's and one
          2channel ADC."

Jurgen Kahrs reports that some old versions of this card actually have 2 dedicated stereo output jacks. He also notes, "The
       Soundblaster PCI 128 is a real pain. We thought about using it in our products. This turned out to be impossible because
       the SB PCI 128 is just a name that Creative uses as a synonym for 'our cheapest card'. The hardware behind it changes
       constantly. On their web site they have photos of two card layouts which show completely different cards. But there must be
       at least one other card layout because we have a version of the SB PCI 128 here which does not resemble any of the two
       photos...."