There’s a lot to be read on this, i suspect it’s related to internal conversion and gain, remember it will sample at 16 or 24bit, so use 24bit to keep the quiet stuff intact and look at the gain threads for ideas
i’ve calmed down since that post as i see the device as a live instrument rather than a dedicated recorder, but it’s good to understand the nuances and get user feedback on best practice etc, make sure your A4 signal is as hot as you can manage too