I changed the drivers to Trinamic's TMC2208. It's pretty tricky though. You need the tools (I had: preheater, hot air, pcb microscope, soldering iron with fine tip) and skills (and nerves ;) ) to desolder the QFN-28 drivers, one 0603 cap and the two 0603 sense resistors near the connector for each of the drivers.
[cap between pin 4 and 5: 100nF -> 22nF, Rsense (2x, on pin 23 and 27): 68 mOhms -> 180 mOhms 0.15Ohms]
EDIT: use 0.15Ohms instead of 0.18Ohms according to the application note and some sources on the anycubic stepper motors)
I changed the drivers to Trinamic's TMC2208. It's pretty tricky though. You need the tools (I had: preheater, hot air, pcb microscope, soldering iron with fine tip) and skills (and nerves ;) ) to desolder the QFN-28 drivers, one 0603 cap and the two 0603 sense resistors near the connector for each of the drivers.
[cap between pin 4 and 5: 100nF -> 22nF, Rsense (2x, on pin 23 and 27): 68 mOhms ->
180 mOhms0.15Ohms]EDIT: use 0.15Ohms instead of 0.18Ohms according to the application note and some sources on the anycubic stepper motors)
Trinamic has an application note on that: https://www.trinamic.com/fileadmin/assets/Support/Appnotes/AN045-How_to_replace_Allegro_A4988_with_TMC2208_01.pdf
Pretty risky (I couldn't find a replacement board online if anything had gone wrong), but the results are very impressive!