What was said. I’m getting more and more blind from using everything with the balanced one. It sounds better to me compared to the 3.5mm with iems and headphones.
A biggest diference than iem vs iem or headphone vs headphone…
Why?
Is this improvement due to using the balanced connection itself or because said connection has more power?
That is, is this improvement in sound quality due to power?
I’m by no means an expert, but The most right answer is it depends. since the balanced output puts out more power it’s easy to sometimes mistake higher volume for better sound quality. But More and more DACs and amps these days are designed to be balanced. Most of the design effort is put into the balanced circuit. The single ended output is usually half the power with slightly worse specs. As a result, the balanced output tends to sound better.
There are still plenty of single ended amps that sound great. Strictly single ended DACs are getting more rare though. The quality of parts used, the circuit, and power supply are more important.
Could be perceived quality differences due to the power level, if you don’t have any way to do very accurate level matching when doing A/B comparisons between the two outputs.
But other than that, the one benefit you should always get on balanced vs. SE is stereo separation (and possibly imaging and detail as side-effects of better separation). That’s literally what “balanced for headphones” was invented to do, and it’s the most probable to be an audible difference the lower the impedance of your headphone/IEM drivers that you’re testing with.
Maybe for some applications 
