Robr45- I don't see what's "completely bizarre" about being reluctant to drag a manufacturer's name into a discussion thread where a lot of folks seem to think there's a scandal brewing. In my humble opinion, your hifalutin tone is what's bizarre. On the other hand, your earlier post was extremely helpful. Thanks for that, whether I deserved it or not.
Speaking for myself, I was just trying to help you figure out a problem. I have no interest in mud-slinging. I am baffled where you might see ANYONE suggesting anything "scandalous"?! I don't see any such frenzied desire to out anyone here...just people trying to helpfully answer your question. In fact, the only one I see elevating the issue disproportionately is you! I agree, it is bizarre that you ask a question and withhold what might be key information in answering it. Without knowing what DAC you are using that's a huge piece missing from the puzzle. As I illustrated in one possible suggestion in my previous post, by pointing out the DAC you are using you might lead to getting much more useful input from others that may lead to a better understanding of what you're up against. You might get direct responses from other people who actually use the same DAC in a similar way, and as Cutterfilm points out, the solution may not be the DAC at all. This is like someone phoning up the CarTalk dudes on NPR and telling them all about this problem they're having with a strange noise coming from their engine and then refusing to divulge the car. You said in your post this is a new source - if it is brand new why don't you ask the question of the manufacturer you seem to believe needs protecting, and or the dealer you bought it from. You may also get more information over on the PCAsylum section at AudioAsylum regarding the iTunes volume control.
Good luck.