Really, not at all. Both USB and Ethernet transfer data asynchronously to a memory buffer inside the DAC, from whence it is typically (in a delta-sigma DAC) upsampled (converted to different data!) into a separate chunk of memory, from whence the new data is clocked synchronously and with high precision into the DAC's conversion engine. The idea that the exact timing (i.e., reclocking) of the arrival of data into that first DAC buffer has any impact on sonics doesn't comport with logic. The other potential bugaboo is noise introduced to a DAC through Ethernet or USB connections. Ethernet is galvanically isolated by mandate of its standard, and any competent modern DAC will offer galvanic isolation on its USB port(s), as well. In the event that noise still actually is an issue in a given system/environment, blindly buying a kilobuck streamer is not a cost-effective way to solve the problem, if it even would.