This DAC does not work with some CD players/transports. According to Topping, this depends on the DAC's hardware. Note that the same CD player works with other DACs, but not with this one. This is a known issue that has been discussed a lot on AudioScienceReview. In my opinion, the D30Pro is therefore a substandard product that should be withdrawn from the market, or at least potential buyers should be informed of this problem before purchase.