Adding a DRO and want to integrate with linuxcnc, recommended hardware?

For SSI or BISS absolute encoders, a 7I96S+7I85 is one possibility

If you're thinking about absolute encoders and upgrading the steppers, you can also look into ethercat servos, but the encoders would be pre-backlash this way.

Thank you all so much for the advice. I just ordered the following:
- 7I85 4 Channel encoder 5 channel Serial RS-422 interface
- 7I96 STEP/IO Step & dir plus I/O card
- DB25M-IDC26 CABLE 18"

And for encoders:
Digital Position Readout, 3-Axis Bluetooth for HiTorque Mini Mill (part number 5514)

It looks like the Little Machine Shop DRO kit uses magnetic strips that have A/B/Z (index) encoders, so I plan to swap out their Bluetooth box for the Mesa 7I85, but since it was on sale getting the Bluetooh box was basically free, so I figured why not get it too.

It will probably take me a while to get everything set up, but I'll report back!

- Andy