Just got in a new set of Audeze LCD-X 2021 leather cup today and about puked when I first listened to them. Horrible. My Austrian K701 with custom amp with bass compensation is way better. Then I found this thread and did the EQ curve on page one and now they sound better than the 701 with custom amp. Like people are saying, these take EQ brilliantly.
A word about the Audeze virtual studio software for anyone interested. It is made by Waves (a large plugin maker for audio production). Waves also sells virtual studio plugins under their own brand, and they include curves for many headphones including the LCD-X 2021. The purpose of these plugins is to provide a virtual binaural perspective of studio monitors in a room playing a stereo source, as if you are in the room. So it is much, much more than just an EQ curve. Grammy winning mastering engineer Glenn Schick uses high end cans and virtual studios these days instead of traditional speaker monitors in a treated room, and he says its on par with the best rooms and speakers, and is completely portable. In one video interview I watched, he's wearing Audeze open backs of some sort...
All that said, the EQ curve in this article is much better than the one provided by Waves imo, and presumably better than the one in the Audeze virtual studio since it is a Waves product. I find that placing the correction EQ from this article *after* the virtual studio (and using no correction curve inside of the product) is superior to using the included EQ curve inside the product. It still affords a quick and painless way to swap from the virtual binaural perspective of speakers, complete with crosstalk and room acoustics of the treated studio (Abby Road One, Ocean Way Nashville, etc. whichever product you purchase from Waves) and an EQ corrected stereo perspective of just the cans (both are needed to do a proper mix). FWIW I am using the Tokyo Dawn Nova GE EQ for this, a fantastic piece of DSP.
Since I just got these today, the acid test is going to be doing a couple of remixes with these. With my 701 setup I was getting the same small issues on every mix, despite trying to do EQ corrections on the cans to get them to reveal those issues. Fortunately the initial listen to those mixes thru the corrected LCD-X revealed those issues the same as my traditional monitors do. Which is encouraging, since the goal is to drop using them (the way Schick did) except as a double check.
So unless the remix tests are a fail and they don't translate, these LCD-X won't be going back. Given how close I was getting with the 701 setup, I'll be surprised if these don't work out, but well see.... I will say I was initially turned off by the amount of EQ needed for the correction, but it does in fact sound great even cranked to dangerous levels. The fact these completely suck without EQ is a bit of a bummer, but for me they are a work tool, so not going to sweat having to add an EQ plugin. And I'll use my 701 setup for recreational listening.