You can connect whatever needed to the front TRS.
Balanced is not limited to XLR, it’s a interconnection principle.
As long as the cables are balanced all through you get an impedance balanced signal from PH3/4 that can be routed through a patchbay of course.
There’s a multitude of balanced audio output topologies.
To name a few:
• Impedance balanced.
• Active (electronically) differential balanced.
• Active differential balanced with automatic level matching when connected unbalanced.
• Transformer balanced.
• Transformer balanced with lifted ground.
They all achieve the same result if used in a studio environment.
The “balanced magic” happens at the receiver, not at the sender side.
The receiver cancels out the common mode noise that might have creeped into the signal.
Example:
All later AKG microphones successfully use the “impedance balanced” topology.
This on the very weak and vulnerable mic-level signals.
So what I proposed is completely reasonable.
Excerpt from Wikipedia:
https://en.wikipedia.org/wiki/Balanced_audio
A common misconception is that balanced audio requires the signal source to deliver equal waveforms of opposite polarity to the two signal conductors of the balanced line. However, many balanced devices actively drive only one side of the line, but do so at an impedance that is equal to the impedance of the non-driven side of the line. This impedance balance permits the balanced line receiver (input stage of the next device) to reject common-mode signals introduced to the two conductors by electromagnetic coupling.
