[monomial]

Oh interesting. The datasheet for the PCM5102A says it supports line-level output with a minimum load of 1kΩ [1]. I think most headphones typically have an impedance of less than 100Ω. I'd guess the excess current results in some distortion or low volumes? It works fine in practice though?

[1] https://www.ti.com/document-viewer/pcm5102a/datasheet

[fsniper]

I only checked it with a mdr-zx770bn. And it was OK. But as I did check that with a breadboard, any noise could be attributed to bad connections/emi.

Now I'll check it when I work on this next time. Probably in the upcoming days. ( Still my current protoboard would be only a tad bit better )

[fsniper]

I rechecked it. There is no noise or distortion. In fact volume levels are pretty good. I am using some digital volume control and can't go too high.