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thanks..anyone use this r501 speaker? can share some experience? 

ok, so that's the reason that it doesn't sounds that good.
when using analog input to your s530d, xonar d2 can produce good SQ because it have a good DAC circuit on the soundcard, while normal dvd player doesn't have a fantastic DAC inside, so it can't produce the SQ as good as xonar d2. basically this shows the importance of DAC and that's why a good CDP selling at those price. it makes difference.

just wonder if your dvd player have digital output? if yes maybe you cant try it with s530d and probably will give you better result.
you just need a good input to your s530d, then you can get good output. thats' simple if using analog input.