Hello,

I am having a strange issue with my ADI-2 DAC and would appreciate some advice.

I am using a high-sensitivity headphone, and the problem is most noticeable from the Phones output in High Power mode.

Problem

When I play high sample rate content, especially above 384 kHz, I hear a clearly increased hiss / noise floor from the headphone output.

The strange part is:

the hiss increases after playback of very high sample rate content
stopping playback does not immediately remove it
the hiss remains until I play a lower sample rate file
after playing a lower sample rate file, the noise floor goes back to normal

So it seems that after playback at very high sample rates, the DAC remains in some changed state, and only returning to a lower sample rate resets it.

Sources tested

I have tested with several sources:

Asus mini PC running Linux
Windows PC
iphone 15 pro

So this does not seem to be limited to only one OS or one source device.

Related observation

On Linux, I also noticed that when the DAC is first connected, I can hear hiss in High Power mode before playback starts.
Once playback starts, even with muted music, the hiss disappears.
If I unplug the USB cable before playback, the hiss can remain.
When I connect the DAC to a Windows PC, the hiss disappears.

This makes me wonder whether this could be related to:

device initialization
sample rate switching
a state change after very high sample rate playback
My questions
Is this a known behavior when using very high sample rates
Could this be related to High Power mode with a high-sensitivity headphone
Does this sound like a firmware/state issue, or possibly a hardware problem

Any help would be greatly appreciated.
Thank you.