[rickymix]

Thanks Dave. I found and downloaded several older Focusrite drivers, and managed to get the Scarlett to work. Kind of.
The Mac's "Audio Devices" sees the "Scarlett 18i20 USB" device, and the word-clock locks in. It shows the correct 44.1K Format and "18ch-24bit integer" Input, and "20ch-24bit integer" Output. ProTools sees the Scarlett as "Inputs 1-8, and all 8 channels record simultaneously, no problem. But the Volumes on all channels, In and Out, are stuck at almost zero.
But a little audio does come through. Singing at moderate volume through a Shure SM57, with the Scarlett's Mic Volume knob cranked all the way up to 10, I get a decent volume, and if I sing loud I can get it to barely clip. The sound quality seems OK; a little raspy, but that could be my morning voice.
It just seems weird that Scarlett mic pres are so low-volume, even compared to my Mbox Gen 3, let alone my APIs. Could that be normal?