So I then decided to enlist the help of Rob Fritz at Audio Art Cable to make a custom XLR-to-RCA cable that makes pin 3 from the XLR connector as the Hot signal on the RCA instead of Pin 2.Can you describe more specifically the connections you were using prior to the arrival of the custom cable? The reason I ask is that many XLR-to-RCA adapters, while connecting XLR pin 2 to the RCA center pin, also short pin 3 to ground (pin 1). Which as I see it makes no sense when adapting XLR outputs to RCA inputs (although it is proper practice when adapting RCA outputs to XLR inputs). Although many designs will not have a problem with that, the output stages of some equipment will not be happy having the signal they provide on pin 3 shorted to ground, and their performance may be compromised. See this thread for example.
As I was waiting for the custom cable, I decided to break in the DAC for a few days with the normal connections.. After about 100 hours, I was not that thrilled with the sound.
So I'm wondering if the difference you perceived might have been due mainly to eliminating an improperly configured adapter arrangement, rather than to correcting absolute polarity. The consensus of many discussions that have been held here about absolute polarity, as I see it, is that it matters mainly for recordings that have been engineered using purist techniques, i.e. a minimal number of microphones and minimal mixing and processing. On other recordings, which in most genres seem to comprise a considerable majority, a multitude of different mics are mixed together and processed with a hodgepodge of random polarities.
Nicely written post, btw. Regards,