I was thinking that the 73 Hz tone is rather pleasant compared to the ~13kHz tone I hear/perceive in both ears almost constantly. It used to bother me a lot, now I accept its presence and try to focus on things I'm doing instead. Of course there's no knowing what the 73Hz experience is like when sustained. My high-pitched tone I attribute to a combination of exposure to loud live music and hypertension from coffee (and to a lesser extent alcohol). The intensity and pitch does vary and often something will trigger the start of the tone in the morning, like the sound of the towel hitting my ears when drying my hair. I've recently cut down my coffee intake dramatically.

I think I agree with you. The low D note I hear must be more pleasant than the 13kHz you hear.