How to verify impedance being used?

Perhaps I am asking the wrong question.
Yesterday I switched from the open Sennheiser Game One to the Closed Game Zero. I see that the zeros require less ohms at 50 now at least. I love my ones but I'm unfortunately in a loud environment and closed is highly beneficial. I will keep my ones and perhaps use again at a later date

I have an ASUS z170 Pro gaming with the Supremefx (Realtek ALC1150 ?) With the 300Ω-headphone amplifier built in. They sound very tinny and weak. I suspect they are being underdriven. I could swear I could set (or at least see) what the impedance was at one point. I'd like to verify (or better yet set) the impedance. When I plugged in headset, I got the pop up. I tried auto and well as selecting the headset over the earbuds.

Windows 10 pro, 64 bit. I installed the latest ASUS drivers Version 6.0.1.7899 from 2016/08/23
I've think I've looked every where and do not see it in the Realtek Audio Manager or in the windows settings.

I started reading the stickys and may try them out. I see about the HDA vs the UAD. I hate to do all that and still not see/help impedance?

Better yet, anyone already go through this with my same motherboard?

Impedance is an electrical property of whatever headphones you choose to use & can be found in the specifications for those headphones,

If your motherboard's limited capability inbuilt amp (ASUS don't seem to provide proper specs on their website or in the manual) cannot drive your chosen headphones then you'll need to get an external amp that will.

I have an ASUS Z170 ROG Maximus Hero VIII motherboard with the same Realtek audio, and the Supreme Fx app.
I have a recording studio and have plugged in various headsets (different Impedances) and have not noticed/heard what you are.
Check the Supreme FX setups/options to see if you can sort it out. I doubt the Impedance of the headset is the problem.

Sorry for the confusion. The correct setting is called amplify level. I don't have this option listed any more. It actually detects and chooses it for you. If it detects 110 ohms or higher, it would select Extreme.

The manual and website say it can support up to 300. I had this setting in the past. That is why I was wondering if I needed a different driver or something. I looked up my DLLs and confirmed I align to FF03 = FF00 with Nahimic Integration driver.

I dont have SupremeFX software, mine is branded ASUS High Def Audio. I dont see anything else for my board to install?
Z170 PRO GAMING Driver & Tools | Motherboards | ASUS USA

Sorry I am not describing this well!
"If your Realtek Audio solution has a dedicated headphone amplifier, set the soundcards output impedance/gain (Ω = ohm) to a value close to the headphones input impedance. Do not set the impedance much higher as it may damage the headphones."
I am now missing this.