with HW mixer set.
If I set SW mixer is OK .
V3.198 connected via HDMI to LCD tv
On my main streamers , RPI4 and same DAC E30 is OK with HW mixer .
What could be the reason ?
On paper yes. But you should test by hearing.
In short:
Noise will not be impacted by SW volume control, so if you have a noise level of 1% at 100% volume, it is 1%. Lower the volume to 50% and noise at 1% => 2% of the signal. Lowering volume to 10% => 10% of the signal.