Lowrider,
My symptoms are exactly the same as yours: live music and canned laughter are killers. I would add that when the harmonic distortion from tube gear comes together at the high end, the effect is ear-piercing to me, but that is apparently not an issue with your ARC.
I did some auditioning of my own system last night and apparently the pre pro and Steve's cable have achieved full break-in because I was quite comfortable with the experience in general. So I'm catching up with myself.
But it requires for me the use of Dolby Volume which I realize will be an unpopular choice for audiophiles. I'm just saying that if all else fails, there is Dolby Volume. It is better than no music. I still plan to try reclocking.
BTW, I think Daedaleus (sp) speakers still use a cloth tweeter. Would be interesting.