Hi -
All this input is excellent, thanks so much! I'm clobbered with work during the week, and it's going to take some time, studying these responses. But a couple comments. My cpu with on-board ALC1150 is not horrible, with 110db S/N on front channels, etc. For my ears, it might be sufficient, if I could remove the hum. I HAVE tried many of the things mentioned... but I will try more... The voltage level of the hum signal seems to correspond with the voltage level of the power supply signal needed for the "processor ON" input. Like, .2v. I think there may be some Siemens computers with a new approach, where this signal is not used (and these Siemens MOBO's use ZERO volts to keep the computer OFF, and thus consume no current at all when turned off.) But anyway... I really don't want to have to buy another MOBO. Maybe a pro-sumer audio card would be nice; like everybody, I enjoy buying neat new stuff. :) I like the idea of using the PCIE bus, to minimize latency for my digital piano. But an external (USB) audio interface would introduce less than 1ms latency, and might be a good practical solution.
I will work thru this and let you know the progress... Thanks again!
John