This cable is driving me nuts. It went from smooth to harsh to bright sounding. Now I've got a soft tube setup, the filter on my DAC at 5 to deal with post and preringing and upsampling redbook to 96. It actually sounds quite good in this set. I would guess I'm past the 100 hour mark.
I was, or rather, tried to play Aerosmith "Pump" but it was unlistenable. Just way to aggressive. Just down the list from Aerosmith was Al Dimeola. Now that was amazing. Then I cued up Jennifer Warnes, Blue Coat CD - remastered. With my critical ear the highs are still a bit lacking in texture. The mids lack some in the warmth department as well but at the same time giving great clarity.
I made a change on my 7 nines silver XLR interconnect pair going from Vampire XLR's to the much higher quality Furutech Rhodium's. This seemed to provide a bit more richness for lack of better term and a bit more air but it's difficult to tell honestly as it took me a few hours to perform that change.
Having the AC12 in the system I decided to sink a ground rod in our groundless rental (that didn't prevent "others" from thinking this service is grounded finding ground wires attached to a groundless pipe)and put my dedicated circuits ground to a proper ground. I can't say I noticed any difference (aural memory being what it is) but at least I feel better ;-)
I'll continue to monitor this AC12 and report back. At some point I'll pull it from the system and return my Flavor 4 for comparison.