roon > dac basic question

Others can correct me since I haven’t had enough coffee yet.

I don't have a streamer. I have had a couple streamers that worked with my dac but I replaced them with the optical rendu, running Roon. My dim understanding is that the rendu is a bridge and connects "directly via usb to the dac." 
 

The OpticalRendu is both a streamer, bridge, and Roon end point. Also correct that the OpticalRendu connects directly via USB to the DAC.

So my question is really: if a dac has a usb input for the rendu, then does it matter if it's "Roon ready" or knows anything about Roon?

Since your OpticalRendu is the Roon end point, the DAC does not need to be Roon Ready or know anything about Roon- as long as the DAC has a USB input it should work.

I'm curious whether I can connect my rendu to a portable headphone dac/amp that has only a micro-usb input and doesn't appear to be roon ready. More generally, I'm curious what I need in a dac to run roon from the optical rendu, other than a usb input. 
 

I can’t see this being a problem, but all you would need is a USB-A (from oRendu) to Micro-USB adapter (DAC/Amp). I’m always cautious when adapters are involved from prior experiences, but logically this should work.

@toro3: thank you! That's exactly my understanding -- and that's my hope about the adapters to micro-usb. I also appreciate that you took the time to wade through my muddled posts. Well done!

Everyone is correct here but saying it differently.

Maybe I can further confuse things: :)

Roon consists of three parts:

-Roon Server this is the computer that runs Roon Core

-Roon Endpoint:  this is the streamer or bridge.  A Roon Ready or Roon Certified        streamer typically will run Roon AND may have its own software to run Music.     (examples are Aurender has Conductor App, Auralic has Lightening app, etc etc.

-Roon Remote: this is how to control Roon, usually an iPad or iPhone etc.

Now there are also Roon Bridges.  These typically run Roon but no other music playing software is offered.

I believe the Rendu's are Roon bridges, where they combine a computer to run Roon Core and also stream music  using Roon (but I am not familiar with these products).

While you don't need a dedicated (separate) streamer if you have an internal bridge, many find a separate streamer will sound better than a bridge imbedded in an amplifier or preamplifier.  

I have a MM Tambaqui.  It has an internal Roon Bridge and is Roon certified as an endpoint. But when I got a dedicated streamer (Auralic Aries), it sounded better;  More organic and lifelike.  Now I also have a Grimm MU1.  It Runs Roon Core (Server), and also is a Roon endpoint. It sounds very very good streaming to my Tambaqui, but offers no other music software than being a Roon Endpoint.  But it is as good as most two box setups, a Roon Core and A Roon Endpoint (bridge).

Finally, to actually answer your question, any streamer or combined server / bridge that is Roon Certified or Roon Ready can output music to your DAC.  It may do this with USB, AES, Coax, Optical, I2s or any  combination of these things.  So a 
DAC does not need to be a Roon Endpoint.  But if it is, it has an internal Roon Bridge or internal Streamer.

Happy Holidays!

The simple answer is, no, a DAC doesn't have to be "Roon ready."  All that software is in your streamer.  It only matters that the streamer and the DAC have compatible output and inputs, respectively--USB, optical, coax, I2S.  As long as you can connect the two units with one or more of those options, there's no problem.

In your setup it doesn’t matter if the DAC is roon certified.