How to get DSD working in a networked (Roon) setup?

Dear,

I recently received a few DSD albums and would love to play these.

In the manual of the T+A MP 3100 HV, I read
"The MP 3100 HV can be used as a high-quality D/A converter for other devices such as computers, streamer, digital  radios etc. which are fitted with poor-quality converters or no converter at all. The MP 3100 HV features two optical and two electrical S/P-DIF digital inputs on the back panel to allow this usage.

A USB-DAC input on the back panel permits to use the MP 3100 HV as D/A
converter for computers.

At the USB DAC IN input the MP 3100 HV accepts digital PCM-encoded stereo
signals with sampling rates of 44.1 to 384 kHz (32-bit) and DSD data with
sampling rates of DSD64, DSD128, DSD256* and DSD512*."

To use the T+A MP 3100 HV to play DSD files, I have to connect it to a PC using a USB cable? Is my understanding correct?

I have all my music on a NAS in the basement. I use Roon to play (flac) files on my stereo. Is there no other way to get DSD to play?

Ideally, I would prefer to add a device in my network to play DSD. 

This "USB DAC" truly puzzles me. 

Thank you for your advice.