I am sorry I just dove in there.
I use to have a head phone set that had a 0.047 MFD cap on the audio leads. Took out some of the hum on the tube radios. I felt it add to hear CW better. sharpened up the 1000 HZ tone a bit.
Stay on course, fight a good fight, and keep the faith. Jim K9TF/WA9YSD