The ESS 9068 DAC chip in UHD3000 costs ~ $500 in a standalone DAC. It produces superior audio quality for those who want the best. Clearly it's not for everybody and the 1619 chipset in cheaper Zidoo products has a good DAC itself.
Other benefits of UHD3000 are 2 x SATA HDD bays, 2 x HDMI ports (vital for some HDMI 1.4 audio setups), more RAM, MQA support via the DAC, and the linear PSU.