[mu-tron-kid]

Originally Posted by guitarman6

Not sure if anyone from AVID even reads this forum anymore, but if they do, I'd love to revive this thread and get an answer to why we still can't simultaneously use macOS Core Audio (System Audio) through an HDX card while Pro Tools is also open? Is it because of the DSP usage?

What is strange is that if I use Ableton or Logic I am able to use my HDX card as the output / audio interface and can also simultaneously run system audio through the HDX card.

As soon as you open Pro Tools though, the AVID HDX soundcard is no longer seen by the computer. It's such a disappointment and seems like something AVID could easily address in the software if other DAWS are capable of doing this; can someone from AVID help me understand why this happens?

This thread was / is originally about a very specific issue where the HD Driver versions were "chasing" apple OS versions, and you literally couldn't access HDX from ANYTHING but Pro Tools.
This was completely resolved in ~6 months via HD Driver updates.

For your issues, the latest PT version solves this by allowing all your "other" apps to play through Pro Tools via AUX I/O.

The reason you wouldn't ever want each of these DAW's to be able to simultaneously play out of HDX is that an Active Pro Tools Session via HDX hardware NEEDS to control the Clock Source and Sample Rate. Leaving this open to AudioMIDI Setup to change willy nilly as you open more and more applications would invariably lead to your Pro Tools Session crashing.
Since Pro Tools #1 function is to record and stay in record regardless of all other "computing" occurring elsewhere on the system, it needs to protect it's software and hardware from having the clock source "taken over".

HDX systems are built to optionally include SYNC Hardware, which is not controllable by any of these "other" apps, so there would always be a conflict if they could all access the same hardware but NOT control the clock source settings.

AUX I/O finally allows us to use ALL these other apps WITHIN the Pro Tools environment, and in a much more powerful way, just like they added Workspace to not only add a built-in "Finder" inside Pro Tools, but to then blow the roof off the functionality generally associated with the standard apple Finder "app"!