Setup for encoder feedback

Hi everyone,

I'd like to add encoder feedback to my cnc and not sure how to best tackle the whole thing.
currently im running open loop with a 4-axis_TB6560 Stepper driver, but i got to change that anyway cause the x-drivers is toast (no clue why, powered up the next day and dead) driving 3 nema23 bipolar 3Nm steppers and 4th axis some time(would like to integrate it once the whole system is overhauled) and my spinle is a 4kw HF one, driven by a VFD controlled via 0-10V without feedback (would like to add that as well).
I'm completely new to that whole mesa stuff and not that well versed with linux. (but got a bit more than the basics of python, and serveral other programming languages)
So my question is:
-Should i buy 4 new closed loop drivers or go for encoder feedback via mesa card (i currently only use the pcs p/port and a p/port pci card)?
If closed loop driver:
-Which should i get (the choice too is overwhelming)?
If mesa's the way to go, thats opening a whole new box of questions:
-What do i have to get for that setup?
-Is the mesa 5i25t a viable option (cause available and got pci on my board)?
-Do I need berakout boards?
-If yes, is the C10 or the cheapo chinese "Mach3 Breakout board" a viable choice (cause i already have one of each)?

Thanks in advance
Greetings Lukas

In general systems with feedback to LinuxCNC are more complex to setup
so unless there is a major benefit (say with linear scales) I would just use standard
step/dir drives, The 5I25T will work with your existing breakout boards.

Encoder feedback on the spindle is useful for things like rigid tapping.

You can also use closed loop step drives but in this case the feedback is just
local to the drive.

Since you are replacing all the drives, EtherCAT might also be an option though
that may make supporting the analog spindle and its feedback  awkward

How difficult is it to implement feedback via the 5i25?

Which cosed/open loop drivers would you recommend?

I figured the spindle feedback would help getting the spindle speed more consistent (had oscillations in speed, but there are several possible reasons for that)

I used to have my steppers running un only 12v which made them quite poor performing. What voltage would you recommend for my steppers?