Things to try solving crackling noise
I do not own a unit yet, as I am somewhere on a waiting list.
But what I can say from experience with recording and repairs
And digital recording, is noise can often be a result of switchmode power supplies.
I am guessing that the fractal gear uses switchmode power supplies. ( does not imply a issue, just a note)
The noise I have dealt with in a recording environment is usually digital sync/ conversion,
Or the noise generated by switchmode supplies.
If you are recording via xlr/RCA outputs and you have digital noise try going via a isolated DI box with the earth lifted.
If you are recording into a laptop, try running it on batteries only.
I have had many times in the studio a piece of gear that uses a switch mode supply, and have been able to eliminate weird noises via using a isolated mains supply (iso transformer) or via a audio transformer DI.
As I don't own a Fractal unit yet I cannot comment on their inbuilt power supply.
recording via a laptop:- the only laptop I have not experienced noise from is my MacBook Pro.
I find dell laptops, and compaq etc their ext power supplies cause noise, whether recording via USB or audio,
But as soon as I run on batteries only the issue is gone, or I use isolation as per above.
Some desktop PC's can be a issue as well.
I am curious to find if this helps, as I am in the market for a new axe fx II, but I would be happier if these issues were not their.