OK-So with the HE 6's which is 50 ohm @83 sensitivity and the Mini X would resistors help or not? If so what value and how connected?
You do not need a resistor adapter of any kind of the Hifiman headphones that are low on sensitivity, like the HE-500 and especially the HE-6. The HE-6 is so insensitive that it is the very reason some of us looked to speaker amps instead of headphone amps to get raw current throughput.
For the HE500, HE4, HE6, all you need is a cable with 4 banana plugs terminated on it or an adapter with banana plugs terminated on it, and an interface that receives whatever cable you have. No resistors involved.
The only place for resistors here is for headphones that are very sensitive and have low impedance, meaning, they hardly needed an amplifier in the first place. To use them with a speaker amp (any speaker amp) you would want to probably introduce a resistor impedance adapter some where in the chain to cut down the noise floor and give you volume attenuation. I only use this for my Denon D5000 which is highly sensitive and doesn't even need an amplifier like this, I just do it for fun.