Finally made some progress.
The first thing I did was to remove the Turtle Beach card and use the built in sound card. Within five minutes I had a real good calibration curve.
Then I did a measurement with the jumper still in place. Guess what, the noise was back. After two hours, I deleted all the files and tried again. Here are the results. The problem was (this is my guess) was that some time ago I made a mike calibration curve while I was having all of the previous problems. Now with the problems gone, when I would make a measurement, the calibration data was being used and the end result was REW was putting the noise back into the data. Does this make since? Tomorrow I will put the Turtle Beach back in and test again.
The top curve is a measurement curve (my speakers test really really flat, don't they - just joking)
The bottom curve is the calibration curve - I'm so happy.
Thanks for your help.
gateway calibration right channel.jpg