I don't have a specific recommendation for headphones to buy....it almost seems like people hear headphones differently, and I wonder if the shape of people's ears have more of an effect on headphone sound than most people want to admit.
Just as an example, I've recently seen a handful of people online saying that MDR-7506s or MDR-V6s are their reference headphones. I've had one set of those or another sitting around since like 2006. They're all crazy bright to me. I like them for specific things and can use them. But, I'd never call them a reference set for me.
I've heard good things about getting headphones from Sonarworks with an individual calibration profile. But...you can't use their calibration with the fractal unless you put a computer in the way of your headphone signal....which is an option as long as you can do it with low enough latency. I almost wish Sonarworks would release a headphone amp that lets you use the calibration profile via DSP by just plugging it in.
What I do is to not use Output 1 for anything else while I'm using headphones/IEMs and put a PEQ block before it. I'll set it up to output pink noise from my computer on both the headphones (through the fractal) and my main speakers (not through the fractal) and adjust the headphone EQ until they sound "close enough".
If there are other issues with your headphones, it won't fix those. But if it's just frequency response, you can probably get a lot closer. Also, FWIW, I don't think I've ever had headphones or IEMs that didn't "require" or at least sound better with some EQ. I also don't think I've used anything "nicer" than Shure 535s, and I don't think I've ever heard anything that was meaningfully better than some of the 5 or 6-driver KZ chi-fi IEMs. I also strongly prefer IEMs to headphones in general for some reason.
