Just curious what multimeter you're using though? My own only goes down to 1 decimal place with regards to resistance measurements. A quick check suggests the 3 decimal place ones cost a bomb with the 2 decimal point ones a reasonable US$50 or less. Can't find a 3 decimal place one anywhere even near US$100. As for the TRN 8-core, bi-colour cables that are going for US$8+ on Aliexpress now, my quick measurements for both 2.5mm TRRS with MMCX and 2-pin correlates well with your measurements. All 4 pins are in the 0.3~0.4 Ohm range for both cables that I bought.