Just got off the phone with the technician, who has been working on my machine for two days. He was working through the onboard sound, not the USB sound card I sent with the PC. However, he plugged USB speakers directly into USB and heard massive static, something I had never noticed. Right now the thinking is defective mainboard.

The incredible news is that somehow the technician ran into the pro sound/recording guy at the music store where I bought the Presonus. They got to talking and realized they were both dealing with me. Now we're all on the same page. The technician knows for certain that the Presonus works. because I took it back to the store and had it checked out. He also understands my mission--recording and mixing music--and says that he'll try to have it ready today, assuming they can find another mainboard. (I know there's one at their store across town, but not where my PC is.)

Onward through the fog.

"My primary musical instrument is the personal computer."