Quoted from Shadrac:
About your first question:
Yes I opened the code with Pinball Browser and don't notice the noise during the Main Theme trough my PC speakers, and i listen it at a loud volume.
I already did that, i checked each speaker individually, the noise is present in each speakers, i even changed the cabinet speaker.
I saw you have a Premium too, can you listen the Main Theme in the Test menu (Diag-Speakers-Main Theme number 1) and tell me if you hear something like my video?
I just got my JP Prem and I can hear the same 8-bit sound once the horns come in during the Main Theme. Also I can hear it on Diag Sound #183 (another horn instrument sound). Like you said, maybe it's when a certain frequency is hit there is a slight resonance, kind of like what happens on a guitar with certain notes. I am not sure this is a sound issue but rather just a frequency thing. It's hardly noticeably but it's definitely there...so you are not crazy .