I run two systems on my computer, so that Windows is not allowed to use my Saffire unless I specifically tell it to.
 
Windows default is set to my onboard Realtek (requires a second sound system), but this also keeps Windows from interacting with the Saffire. In the sound card properties, I had to explicitly tell Windows to use the Realtek (with both online), and have both "Exclusive Mode" options (Sound Card Properties->Saffire->Playback Properties->Advanced) checked for the Saffire.
 
I do remember that before I did this, Windows kept trying to be the "priority" with the Saffire.

I found another forum thread on a different site where several people were having this exact same issue. It appears that the solution is to use 1/4 TRS cables. After scrounging around in here, it appears that all I have are 1/4" TS unbalanced cables. I don't see a single stinking TRS cable in here to test with. I'll pick up a couple from Guitar Center tomorrow and see if that fixes it. If it does, I think we're in business. 

Holy cow. I found two TRS cables and tried them out. No noise. I feel like such an idiot. lol   This entire time, I've been fighting with this because I had the wrong cables. I just never thought about it. I was using the same cables I used with my previous interface and it sounded great. hehe   Oh well, it pays to pay attention to the instructions and to know a bit about what you're doing, which I apparently do not. I swear I used to know some of this stuff. This is what happens when you get away from it for years. lol Don't ever do that!
 

Awesome! Balanced cables work wonders  Definitely check out the MixControl video when you have time, since that software is very powerful once you understand it. I am glad you got it working.

mettelus
Awesome! Balanced cables work wonders  Definitely check out the MixControl video when you have time, since that software is very powerful once you understand it. I am glad you got it working.

Thanks! I really appreciate everyone's help. My lack of patience has gotten worse considerably as I've aged. lol  I was about to throw this stuff out the window and go play a game or something. :)  Now I need to spend some time watching videos to refresh my memory about how to even use Sonar. It's been a while.

As far as the advice that some of your devices need to have different electrical sources on different circuits is in fact the opposite of what you need to do. Best is to have all your devices on one circuit and have all the earths connect back to a single point.

When you do that you also bring two different grounds/earths into the process and that is one of the most common causes for ground loop hum.

http://www.motu.com/products/avb/ultralite-avb

Glad you found the solution, thanks to this great forum. I have found that for me it really pays to buy things I don't understand from large distributors of electronic gear. They make sure that I get the right stuff, and that I know how to hook it all up. Otherwise I would be even loster than I am.

mudgel
As far as the advice that some of your devices need to have different electrical sources on different circuits is in fact the opposite of what you need to do. Best is to have all your devices on one circuit and have all the earths connect back to a single point.

When you do that you also bring two different grounds/earths into the process and that is one of the most common causes for ground loop hum.

Just seconding this as truth!

neiby
Holy cow. I found two TRS cables and tried them out. No noise. I feel like such an idiot. lol   This entire time, I've been fighting with this because I had the wrong cables. I just never thought about it. I was using the same cables I used with my previous interface and it sounded great. hehe   Oh well, it pays to pay attention to the instructions and to know a bit about what you're doing, which I apparently do not. I swear I used to know some of this stuff. This is what happens when you get away from it for years. lol Don't ever do that!
 

Congrats! Glad you found the the solution.