Where did you read that? The Auteur's are supposed to be the most neutral out of the 3 TOTL headphones and, having heard the Eikon (slightly warm) and Atticus (warm), that wouldn't be dark at all...
I'll be getting the HP-3 today and will do some out of the box sound impressions, burn them in for a week straight, then some final impressions. I've been looking for a more natural TH-900, so if these don't cut it, I'll return them and just go back to the Fostex.
From cskippy: https://www.head-fi.org/threads/zmf-auteur-thread.862918/page-30#post-13891332
"System Synergy
I need to point out that the Auteur will probably be too warm and dark coming form most headphones, even the HD650. I was initially put off by this but instead decided to rework my system to be brighter to suit the Auteur since it did so much right. I changed my interconnects from Blue Jeans Cables to Pangea and the Auteur became much more neutral yet still musical and pleasing plus the sound stage just opened up even more. I plan on getting a silver cable for the Auteur to get the last bit of treble extension and tightness in the bass. If you find yourself wanting a little tighter bass and more treble, give the Pangea or maybe silver interconnects a try with the Auteur"
I used to own the ZMF Eikon and Atticus, but decided to sell both because I wanted a more open/airy/transparent yet not as warm sound signature/presentation. The Eikon however were my preferred choice between the two due to a better tonality and resolution overall.
I decided I'll be a guinea pig and try these out as well and will provide some impressions/comparison soon!