Hey Lunahorum, I think I may be having the same problem you had with respect to level of amp noise. I'm directly connecting my guitar into my firebox, and getting some amp hiss thorugh amplitube and the vsts posted on this thread. I thought it was normal at first, like a part of the amp simulation, but you posted that you got rid of it.
I couldn't gather how you did it from your post. You mentioned getting an audiophile 2496. From what I could tell it seemed to fix your problem somewhat. So I guess it might be my firebox, but I'm not sure. If you could elaborate more on what exactly you did, that'd be a big help to me.
Edit: Crap, sorry about the off-topicness. Only just realized I could have sent the user a pm instead