trying to reduce constant hum in piano recording

[BLevy]

This is in answer to Bill Odom & Administrator: I put a sound board into my computer along with the Krystal board. When I go to Dnoise, I am able to play through the new sound board when I punch Bypass Play. So I know sound board works. However, when I try to play selected piano segment with a less than 1 second wave file of "hum", there is no sound at all. I am not able to adjust parameters of "P"button.

When trying to play through Preview, there is no evidence that anything is playing. Suggestions, Please!!!!