You'll need something between either of those USB-serial converters to interface to the DAC, as you mentioned in your original post. Those converters will not connect to the DAC appropriately, nor will they provide an appropriate MCLK, BCLK, LRCLK, synchronised data or provide a continuous jitter-free data stream.
The interface could be made with a microcontroller, CPLD, FPGA... depending on what sample rate you're expecting, the choice of hardware might change also.
The software on the PC - if you're going to use a USB-serial converter - will have to open the port and send data down it. You'll need a custom program to use your DAC (ie it won't turn up as a sound card to your OS, unless you write a driver for it).