I removed the SoTM from my setup and this is how it looks like:
Intel NUC (Roon server with ROCK OS) -----> USB----> Empirical audio Off Ramp 5 DDC and reclocker ----> SPDIF ----> DAC.
I choose “Off Ramp” on Roon app to play my music. In this situation, is my off ramp considered my renderer or player? or is the music player on my NUC on the ROCK OS?
As of my understanding the Roon Core is the player (takes the file, plays it and sends the resulting digital audio stream to the endpoint). The term might get unclear when playing streams from Tidal, Qobuz or Internet Radio but Roon keeps to be the player as it provides the playback controls. The Off Ramp is the endpoint for the audio stream as far as Roon is able to see it, but the Off Ramp is a bridge that recklocks the signal and does a format change to SPDIF and sends (forwards) the digital audio to your DAC. The DAC then converts (renders) the digital audio to an analog signal.
Thanks. Let say I introduce a Network streamer like auralic G2 in between.
Nuc to router
Router to auralic
Does this mean now the music player is going to be the auralic?
I think you need to change your Nic 
If you use Roon and because for Roon all music is played from/through the Roon Core I would say no. The Aries G2 is just another endpoint. Things might change outside the world of Roon (hint: UPnP/DLNA) but not for Roon.
In between what? I’m not familiar with the products you use/name here.
Router
| – LAN --> Roon Core – USB --> Off Ramp – SPDIF --> DAC
| – LAN --> Aries G2 – ? --> ?
Why do u say that? and what are some good replacements?
Seems you are not quite superuser yet imho. I’m being funny.
G2 is a transport so no analogue output so it’s only part of the chain…
The Off Ramp DDC is the end point. The SPDiF feed is irrelevant to Roon.
Brains trust- so I will soon be adding the Off Ramp 4 to my system, running Ethernet from the Off Ramp to the I2s DOP connection on the Ayon Stratos. So I will add this device and then the Nucleus will see the Off Ramp as the end point? It will no longer see the Stratos as the end point? (Currently running USB from Nucleus to the dac).
Haha yes, its an automatic name Roon gave me lol.
Yes you will see the offramp on Roon. How do u like the off ramp so far? I have the off ramp 5
Hullo and apologies for the slow reply. I like it, I use it to convert USB to I2s and then the signal goes to the Ayon Stratos dac via a Revelation Audio cable. It’s sounding very special. As some may have guessed DOP didn’t compute but the I2s connection works beautifully.