What are "true" balanced connectors

Balanced means that the + and - amplitudes of the signal are referenced equally to ground. 

Not a requirement when using transformers which are not center tapped, as was the case for many decades. In the old days, you'd use a single amplifier output, to drive one side of a transformer, and the resulting output had no reference to ground, only to each other.

It is only in modern times that we can use multiple op amp stages as the sender and receiver. And still, the receiver does not rely on any ground reference.

Best,
E

@luynes
You don’t have a clue as to what the ’balanced’ spec is.  This is evident in your original post.
I just pointed you to a person who has experience with Balanced Topology. 
That you find that unacceptable is your problem.
And, if you wanted to know if the amp was truly balanced, why not contact the manufacturer directly, instead of soliciting guesses from those that don't even own the unit?
B

@erik_squires 

Balanced signals used to be transmitted by transformer outputs and inputs which were galvanically isolated. 

Best,
E

Galvanic isolation isn’t a requirement for a balanced circuit. The transformer output, unless it is center tapped, is only differential, which is where the value is anyways as far as common mode noise rejection is concerned. 

Galvanic isolation isn’t a requirement for a balanced circuit.

True.

The transformer output, unless it is center tapped, is only differential, which is where the value is anyways as far as common mode noise rejection is concerned.

Yes, but it proves my point: The + and - are not necessarily referenced to ground. This is something which has just come about because we now use inverting op amps to drive the (-).

The plus and minus halves of the signal can float with respect to ground.  Or not.