White Noise in earphones

Most likely, the Yulong DA8 II headphone amp section has some self noise. Since the sensitivity of the SRH 840 headphone is much lower than the Aonic 5, it pushes the noise below the threshold of hearing.

This means that the measurements and specs on the Yulong website are probably referenced to the DA8 II in DAC mode and not taken from the headphone out.

For the HRT HeadStreamer, it's a bit strange that the noise is related to the Windows system volume. Are you sure that Windows / foobar is giving you the correct sample rate / bit depth for the music you're listening to?

My suggestion is to find an amp that offers a very high signal to noise ratio even at very low power. A JDS Atom seems to fit the bill and it's fairly inexpensive. Try hooking it up to the Yulong in DAC mode. Hopefully you'll have a noise free system with your Aonic 5.

HRT HeadStreamer: Are you sure that Windows / foobar is giving you the correct sample rate / bit depth for the music you're listening to?

>>100%. If I watch a youtube video: 48k. If I listen music in foobar 44.1k or 96k depending on the source. For foobar I use Wasapi.

>>Changing the volume in foobar has no impact on the noise. Only the windows volume (I use windows 11).

I think you are right, this is related with the how the Yulong works (not a defect, but maybe a bug). Adding just an amp sounds like an acceptable solution to keep the DAC quality of Yulong. I will look into it.

Any other option than the JDS Atom? Something older that I can hope to find second hand?

Thanks! great input.

Actually this review mentioned the IEM problem (they called it "hiss"): Review

I try to convince myself that the sound quality of the HRT Headstreamer is the same of the Yulong and that I don't need anything else, unfortunatly that is NOT the case. 

I also try to convince myself that the Aonic 5 get me the best sound, but it falls so much short of my Totem Mani 2....