I have build a lot of 3D printers. Most of them were using A4988 drivers and trust me, they were quieter than Duet which should be quieter. (because of 1/256 microstepping) I have also printer with TMC2208, so I think that loudness should be somewhere in between of these printers.
Btw. The problem is that even on idle it creates a lot of noise. It sounds like the fans are spinning but there are no fans yet. This noise is amplified when doing moves even with slow speed. And that's worrying me. When I turn spreadCycle on it's 2x times louder! I'm not a newbie in this topic I'm trying everything I can before I ask someone for help.
With settings from Marlin it sounds smoother, I would say that it is less rough.
If someone wants code to set these settings in Duet (It's for 24V PSU):
M569 P0 C66180 ; set drivers. toff 4, hstrt 0, hend 5
M569 P1 C66180 ; set drivers. toff 4, hstrt 0, hend 5
M569 P2 C66180 ; set drivers. toff 4, hstrt 0, hend 5
M569 P3 C66180 ; set drivers. toff 4, hstrt 0, hend 5
M569 P4 C66180 ; set drivers. toff 4, hstrt 0, hend 5
Values are scaled to match Marlin values.