Seems to me the signal is much more resilient than single-ended connections. They also seem to have more gain. Why doesn’t everyone use balanced? Or do you all?
Or do you consider it equipment-specific? i.e. the balanced output on device A is better than the single ended, but not so on device B? Or synergy between the output and input on A to B?
Audiophiles should love them, as they are naturally mono-directional! 
For 2-channel, probably, but if you’re talking headphones, probably not. See:
Interesting watch. But his basic argument is that balanced headphones are inconvenient. Headphones are also usually a pretty short run.
Yes I agree that this logic probably doesn’t apply outside of headphones.
I use balanced if it’s available. Lower noise, not much difference in the prices of cables from a decent outfit like Blue Jeans Cable. I can’t think of a downside.
Also, with 4V output rather than 2V, you can use lower gain power amps. Such amps tend to have better S/N ratio.
A balanced connection separates the two signal leads (plus and minus, if you will) from the ground. Unbalanced combines the minus with the ground. But since a headphone isn’t grounded, it can’t tell the difference, it reacts to the voltage difference between two connectors, same thing.
For connectors between equipment that is plugged into the wall, balanced connectors can reduce some noise (common-mode noise, such as RF that the cable picks up). If you have problems with such noise, balanced would help. If you don’t have problems with cable-induced noise, balanced won’t improve sound quality in other ways.
(Two special-case observations:
Rob Watts of Chord has pointed out that the output of DAC circuitry, at least his DAC circuitry, is inherently unbalanced. He doesn’t have an extra gain stage for his headphone output, the output stage can deliver several watts, he is very focused on minimizing the number of active stages. But to make it balanced, he has to introduce an extra stage, an inverter that creates the negative signal, he says that reduces the transparency. On his equipment.
The other side: I have a Hifiman Susvara that is very difficult to drive, requires huge current (power), and the balanced circuitry delivers more power, so I have to use that, ultimate transparency be damned, and the Susvara are fabulous.)
Now that was a nice reply, saves me a lot of typing 
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As a short summary : nobody will argue, that a real balanced interconnection is indeed (technically) the best way. In some cases you simple HAVE to go balanced. Long runs of wires, or when in very electrically noisy situations. I would go balanced, if all my systems supported it…
But when it comes to headphones : no, that it not actually a balanced connection. We should find another word for that…perhaps bridged loading or something. Yes, I do use it. But only because my headphone amp is lacking a bit of power without it. Ideally, the single ended amp should have been designed differently, with more output voltage/power.
Thanks everyone for the feedback. I’ve deliberately tried to weight gear acquisition towards having balanced options. One thing I use it for is I have a home=brewed XLR patch bay that allows me to quickly switch preamps and power amps; for one thing that allows me to switch to my surround pre/pro for movies and 5.1 music. I have found that just using balanced patch cables is the best way to avoid signal loss in switching gear, far better than switch boxes.