I just pulled up the last 32-bit float recording I had made to find out if I could see and hear the problem being described.
Short answer: See? Definitely. Hear? Absolutely not.
See the attached screenshots from RX. This recording was 32fp/96kHz using my F6.
1. Hand Claps - You can clearly see the windowing as the noisefloor increases around the louder transients.
2. A Cappella - The three transients just right of center are accented syllables in the choir. You'll also see stray moments before and after where the converters switch.
3. Noise Zoomed - As it says on the tin. This shows why the added noise is inaudible - it's only showing up above 35 kHz or so.
So, is this still a concern from a sound design standpoint when captures will be pitched down, as shown in the video? Sure.
Is it a concern for studio or live music recording? Well, the noise floor
is constantly shifting with the auto-ranging ADCs, at least on a Zoom F6. It's not just on the stray loud transients; it's happening frequently. But the noise is in a place that no one can hear. While I don't like that this is happening at all, it's not causing any problems in the audible range.
If anyone has a Sound Devices MixPre-II or one of the newer Tascam recorders that have auto-ranging ADCs, it would be helpful to compare their behavior.
EDIT: A user on GS has tested a Stagetec Nexus Compact and it does not do this. Maybe it's a Zoom implementation issue?
https://gearspace.com/board/all-things-technical/1425826-problems-32-bit-float-sound-design-pitching-down-white-noise.html#post16963512