Not sure if I exactly understand your concern. I have been using my Exasound E28 DAC to do this with JRiver for several years via USB2. Kal Rubinson and many others have been doing it as well from JRiver in Mch and in Stereo. Exasound provides a custom Windows ASIO driver that accepts PCM up to 384k and up to DSD256. I have used those formats/sampling rates successfully and enjoyably, and setup was simple.
Presumably, your DAC comes with a similar software driver to interface with JRiver and to support those formats and sampling rates and transmit them to your DAC via USB.
I do this playback entirely from files maintained in JRiver. FLAC and DSF files are no problem and they are how I maintain the bulk of my media files - thousands of them. DFF files are problematical in that their tags cannot be stored in the media file, but they can be played. So, I recommend against those. However, there are DFF to DSF conversion tools.
I have not done Hi Rez streaming, in the direct input from the Internet to JRiver sense, if that is what you mean. I have only used stored media files as input. But, there have been few available sources to date for Hi Rez internet streaming, as opposed to file downloading. But, I do not see why JRiver cannot stream those formats, though setup to receive those streams into JRiver might be more involved and is beyond my current expertise and needs.
Google the following for more info about configuring JRiver for Hi Rez output:
JRiver Audio Setup
JRiver DSD
The likelihood that JRiver would disable those capabilities now or in a future release is quite far fetched and inconceivable.