Some fresh reports on FB are indicating that the latest units (purchased after March) are totally fine.
Audio engineer here. Just received a brand new 16" MBP purchased a week ago. Updated to 10.15.5. Can confirm that the crackling is happening. It occurs on both internal speakers and headphones. Adjusting the sample rate makes no difference. High/low CPU load makes no difference.
Can't speak to whether it's any better or worse than previous OS versions or earlier hardware runs because this was my first experience with a 16".
It's possible Apple is sourcing multiple sets of audio hardware and some people actually do have functional machines. But many people are also incapable of critical listening, so who knows.
Not sure if this has been mentioned before, but a workaround is to use headphones with Apple's USB-C to 3.5mm adapter instead of the built-in 3.5mm port. The adapter has its own DAC, so it bypasses whatever garbage is happening with the internal audio hardware/software.
That's right... the DAC in an $8 dongle succeeds where the internals of a $3000 machine fail. What a joke.