Right. Can we at least agree that the differential part is what helps with avoiding ground loops?

The differential part means that the noise injected by ground loops appears as a common mode signal on the differential pair - that part is correct.

The effectiveness of the rejection of that common mode noise on the differential input depends on the degree of balance in the impdances. Lets look at the maths - and using the CMMR calulations shown by Bruno.

Lets assume the balanced input has a 10K input impedance that is perfectly balanced. The output impedance is (say) 200ohm.

For a balanced ouput using 0.5% resistors, then the mismatch on the output will be at most 1% = 2 ohms

CMRR = -20 log(2/10000) = 74dB

For an unbalnced output, with the ground separated at the output to shield and cold connection:

Then the mismatch on output impedance will be the full 200ohm.

CMRR = -20 log(200/10000) = 33dB

So that 33dB looks pretty good compared to a typical RCA unbalanced connection - but bear in mind that is at the input to the diff amp. Imperfections in the electronics will reduce the CMRR further.

Probably in most systems - even ones where ground noise is a problem for RCA connections - the improvement will be enough. But I'd guess that in systems where ground noise is severe, then the loss of 40dB rejection can make the differerence between the noise being audible or not.

Put it this way - if your system SNR is ground noise dominated, then the difference between just differantial - and balanced differential in the situation above - is 40dB loss of SNR.

On the other hand - the system SNR improvement (again if ground noise dominated) going from RCA to pseudo differential should be 33dB