Hi, my two cents on the topic, based on the experience in the last months.
I had 2 x AKG K271 MkII (closed) due to previous mixing and modeling stuffs. And they drove me crazy because it was really difficult to manage the sound tweaking. Then with the KPA the result was worse than ever. A simple dB/Freq diagram oh that headphone helped me to understand that the purchase was a mess. Not for the headphone itself, but for the application.
After several tests and comparisons, including dB/freq diagrams i switched to a BeyerDynamic DT880 Pro. Such a phenomenal linear headphone, specifically done for mixing/modeling. It is such a great balanced object. The next big feature is that the DT880 is "half closed" , so it is perfect if you play KPA per headphone for long sessions. A full closed is definitely more "fatigue" for the ears.
As mentioned. i have a small headphone amp too to optimize the DT880 performance. Thomann sells small headphone amps for small money and they are valid and good.
The 2 AKGs? One was sold for "partial financing" the DT880, and the other one is used by my drummer as "his session monitoring" headphone.