Just a brief word about DDCs. The Phoenix was diacussed towards the end of the Musetec 005 thread where it was compared to the far less expensive Singxer UIP-1 PRO. IIRC the Singxer has about the same clock, galvanic isolation and a simpler power supply. Singxer has a very fine reputaion for its devices. It is currently available at Amazon (US) and is returnable. So one can try with zero cost. These are USB-in/USB-out devices.
Other DDC devices that were mentiond are USB-in/I2S-out devices. These units duplicate what each of the Musetec DACs does internally. Some have reported that the device made by LKS actually outperforms the internal function in the DAC. Others, me included, are sceptical. Singxer makes a similar device.
Finally, though not usually called DDCs, are Ethernet-in/USB-out devices, better known as streamers. They avoid any use of USB at all. There are those who swear by them. Some such units also have coaxial SPDIF and/or AES/EBU outputs. The jury is out on which of these outputs is preferred by owners of them. However, the I2S can handle very much higher sampling rates than the others and even higher than USB.