(I've converted 3 pairs of older SMC HIFIMAN to 3.5 mm)
3.5mm connectors, requires the least amount of drilling. The miniXLR will be a tight fit, avalable surface inside the driver housing is the issue.
Every cable can be converted to balanced operation, just replace the connector for a balanced connector (4-pin XLR, 4,4mm or 2.5mm are the most common).
Every driver (except electrostatic headphones, STAX) has 2 connection points, one for (+) signal and one for (-) signal. So that means there is 4 wires inside every headphone cable.
I used this on my HE6
https://www.aliexpress.com/item/4001063855295.html