I have used the 803D for the last 3 years - they are not by nature bright - in fact the aspect I most value is their relaxed fatigue free sound. I also use Audioquest cables, so they not the problem.
So look to your other components. Also check your component mains grounding to ensure that there are no ground loops. Try borrowing a matching good quality CD player and integrated amplifier to simplify the wiring permutations.
So look to your other components. Also check your component mains grounding to ensure that there are no ground loops. Try borrowing a matching good quality CD player and integrated amplifier to simplify the wiring permutations.