My attempt at adjusting the (1) Pro's sound. I'm experienced with audio and make music myself, so I appreciate having the ability to adjust the sound this in-depth.
That being said these headphones have some severe sound quality issues... that shouldn't be a thing in $399 RRP headphones.
So while it kind of feels like putting a bandaid on an open wound, but it does help. I like the sound of this EQ for casual use. I wouldn't use these headphones professionally though. Not on the Flat EQ setting either.
The issue
The headphone has a LOT of variance in the treble, depending on how it fits on your head. This means that some of the high frequency sounds can sound nasally, hollow or just off really quickly depending on your fit.
To put that in perspective: while the fit remains secure, leaning my head forward is enough to make the treble sound significantly different to me. It's that bad.
What I changed
The lower end is a little more of a preference judgment; they're honestly pretty good out of the box. I just wanted a slightly fuller sounding (to me) body in the bass and lower mids.
The treble isn't good. Songs with a lot going on in the higher frequencies (...so most songs) tend to sound nasal and slightly hollow, probably due to the dips in the 3-4kHz range, peak around 5kHz, and another dip after.
To adjust this I've lowered the Precision driver by a significant amount and "moved" some of this performance to the Main drivers, while keeping in mind the peaks already present.
I feel like this removes some of the variance in the treble & high-mid frequencies. Basically: bringing the 3-driver set-up sliiightly back to a 2-driver set-up. It's a little silly, yeah.
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My findings are supported by the measurements in the reviews by headphones.com and soundguys.com. (No affiliation, their graphs were just useful to double-check if I wasn't just hearing things!)
EQ made with Firmware Version 1.0.1.53 (They might've adjusted the sound in later versions.)