Audio Research Dac8 question

Hi,

Was evaluating the Audio Research Dac8, Heard the Copland CD player go into a Dac8, then into a Krell integrated and Martin Logan Ethos. After that, the Copland CD player directly into the Krell minus the Dac 8. Both were fine. There might have been differences, but nothing to choose from.

However, I then connected the Dac8 to my Mac via a Transparent USB, and played the same song in Flac lossless. It sounded awfully bright. I have tried playing this lossless through other Dacs at other dealers, and this hasn't been the case.

Any idea why? This is the first time I heard a Dac8, is it known to be bright, I seriously doubt that given AR's reputation, and if it is, shouldn't the same sound have come out when the Copland CD player was connected through it?