Right, so balanced DACS/amps in terms of ground loop eradication are only useful and "necessary" in situation where you have other amps or active speakers connected further down the chain, in which cases you use the balanced input connections of said amps and speakers (whilst headphones & passive speakers won't benefit from any ground loop aspect).
Pretty much.
If you have ground loop noise current, then it "gets on to" the signal "along the length of" an unbalanced ANALOGUE interconnect.
While digital cables can conduct ground loop currents along their ground connection, there will be no noise added to the signal (unless the ground current noise gets so bad it corrupts the digital signal, but then you'll get dropouts and clicks, not an audible version of the ground current noise)
So in the case you have a PC connected via USB to the DAC, the PC noise can conuduct via the USB cable to the DAC, then on through the analogue connection to pre-amp or amp (or active speakers), then back to earth via the ground connection of pre-amp or amp. It is on the receiving end of the analogue connection that the noise gets added to the signal with an unbalanced connection. The longer the analogue connector, the more noise there will be (it is related to the ground impedance between the two devices**) This is why there is more frequently an issue with analogue connected powered/active speakers or subwoofers.
With balanced connections, the noise gets added to both the positive and negative signal, so when the negative is subtracted from the positive the noise cancels out.
So you can solve ground loop noise either by using balanced interconnect (for all analogue connections in the chain) - OR by breaking the loop by using a USB isolator, or a TOSLINK connection from PC to DAC. A cheap USB to Toslink converter will do the job nicely.
With digital connections to integrated amps, or to powered speakers, there is rarely (if ever) a problem since any analogue interconnect between DAC and AMP only exists internally to the amp and is too short to have a problem. Further, proper internal ground design can straightforwardly eliminate the issue.
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**hence analogue interconnect with better/lower impedance ground/shield can also reduce the problem - though not eliminate it.