Skimmed through the previous post and don’t recall the mention of balance circuit will drop the noise floor by 3db which I believe is because it does not tie the ground to the chassis so you’re picking up less noise; those that are techy I’m sure will chime in and explain better.
Ideally the interconnected components will connect the shield of a balanced cable to chassis, which allows the shield to act as an extension of the shielding provided for the circuitry in each component by the component’s chassis.
However some and perhaps many designs connect the shield of a balanced cable to their internal circuit ground instead. (In a good design circuit ground and chassis will not be connected directly together; instead a resistor is often used to connect them together, although there are other approaches that can also work well).
Connection of the shield of a balanced cable to circuit ground within a component, rather than to chassis, can be conducive to ground loop-related noise. See the following excellent paper, as well as item 2 in my first post above:
https://www.ranecommercial.com/kb_article.php?article=2107
So this is one of many ways (I mentioned others in my initial post in the thread) in which the balanced vs. unbalanced question is dependent on the designs of the specific components that are being connected. "Dependent" in ways that often have little if any predictability.
Regards,
-- Al