There is something else strange happening, in terms of getting the PreSonus settled into my computer system....
1. I used it to record Voice (mono) + Piano (stereo) onto relevant tracks in Cubase. That seemed to work ok as a test recording (my performance mistakes are irrelevant to the issue - lol).
2. I then played the recording back, and was able to listen to it through a nice pair of Creative Labs computer speakers, that I connected to the Phones output of PreSonus.
So sound is obviously getting into and out of my PC.
However, I often watch 24 hour News TV on my computer, if I want to check the headlines - and I can watch films too, if necessary. But, I can get no sound from my PreSonus mixer from Internet TV or streamed movies. I ran a control check by turning off my PreSonus mixer, and rebooting with the Alesis turned on (and plugged the Phones connection from Alesis to my speakers, of course). The sound was fine from Internet news tv. I find this puzzling.
Maybe what is not letting me stream (as shown by the But_t ViewMeter) is something to do with the PreSonus mixer failing to get sound from the PC. And yet it did from the Cubase recording.
In sum, I think the PreSonus mixer looks very good and I hope to start using it both in my home studio recordings, and my streaming. If you have any thoughts on all these teething problems, though, I would be most interested to hear them.