Yeah, I believe binaural beats are meant to be listened to at low volumes. But listen at whatever volume you're most comfortable with. The volume isn't crucial.

I'm itching to try to this out later today myself. I've done a ton of hemi-sync as well as my own beats with very inconsistent results. Sounds like the OP's file is producing results. Although, I thought that you were supposed to use theta waves for spiritual purposes? I thought delta waves just made you go to sleep?