Well, may be we will have some snow here in the central parts of Switzerland in the winter!
I have news for you!
My DPS is working again!
I was thinking about how precisely I installed Boom 3D and remembered suddenly, that Boom 3D asked me the permission for the microphone in the security pref pane.
So I installed immediately a new copy of DPS, installed and activated it (and yes, there will be a blue DPS icon in the menu bar, indicating that DPS is processing sound).
I hadn’t a keychain request nor security hints. So I allowed manually DPS in the accessibility tab of the security pref pane and also the microphone in the microphone tab.
With a little shiver I opened iTunes and voilà: There was sound!
I hope this will help you, if it’s not the keychain issue you mentioned…
BTW: Boom 3D is charged, like DPS