I typically run a an audio processor on one of my outputs that goes audio output -> audio processor -> audio distribution
This is typically for the main feed background music that compresses the feed and does some auto-gain control (like a radio processor)
I know there has been talk of allowing a ‘line-in’ input for a phono or other input, it’d be great to be able to have this act as an audio insert.
Really, I must have missed that discussion. Hmmm.
Are you asking for Roon to incorporate an Analog Digital Converter ? That would be a big step outside the product vision described to date by the devs.
Closest I’ve heard to a non-file input is allowing us to link streaming URLs; still digital.
Actually, as far as taking in something from an external source Room calls this an “Input Device”. It’s something they would really like to do at some point. (Think playing a Phonograph in multiple rooms)
In any case, this could also be accomplished digitally by allowing something like a VST insert on the source.
Perhaps that’s a better way to go. Then it could be used for DSP or hijacked to loop in a true insert.
Can you recall where that discussion was ? Not something I’ve seen.
Brian recently indicated VST is unlikely in the near future.
I’ve got the reference 
This is a product idea that we’ve been discussing internally since at least 2008, if not earlier.
The more time passes, the less it comes up. It would be a nice feature for phonograph and terrestrial radio users. I’m not sure whether it would work well synced up with a screen, because all of that transmission, conversion, and re-transmission is going to add latency, some of which might be difficult to model.
RAAT is capable of supporting use cases like this. Of course, we would need to build the “input device” piece. This isn’t in the schedule right now because we have a lot of other priorities stacked up right now, but I would love to see it happen someday.
Brian recently indicated VST is unlikely in the near future.
I did. But we’ve been discussing some product architecture that might make it possible, too. This in the “maybe” category for now.