Optical Isolation

I have read many a discussion here on AG regarding digital but, I still need some further clarification on the best way to go.

Looking at the Sonore Optical Rendu, which only seems to be sold through Small Green Computer.  It's advertised as a "network player and network streamer" which makes it sound like I do not need something like a BlueSound Node, an ifi Stream, an Innuos Zen or the equivalent, or do I? 

At present, I have a DAC and only want to stream music. I've had a Roon Nucleus in the past and enjoyed it, but only wish to use Tidal, Qobuz, Spotify or Amazon Music at the point in time.

It sounds like optical isolation is the way to go. I just want a simple, clean & quiet set-up, so any advice on this would greatly be appreciated, thanks!