The D1 is a gem. Easy endgame headphones. I don't know if it's possible to achieve any more in terms of DD sound reproduction in sub 1k price range, but it sure seems unlikely. But there are caveats.
The good
The D1 are spectacular in terms of sound. The many positive reviews confirm this. Now that I finally heard it myself I agree wholeheartedly. I don't even think the upper peak needs taming. When I subdued it a portion of the energy and sparkle got lost, which detracted from their character and amazing upper end timbre. They're brilliant, especially for instrumental music and vocals. With harder/harsher sounding music it may be sensible to EQ but I very rarely listen to these genres. While listening to my favorite music the D1 produced moments where I experienced music on another level, as if it had physical form and tangible texture. I never had this experience before with another pair of headphones.
Comfort is a big one with headphones. Fortunately I found the earpads very comfortable. They're just deep and wide enough that they sit comfortably around the ear without causing any discomfort. The foam feels good and substantial, I wouldn't worry about having to change the pads too often. The overall clamp force is just right. Not too strong but at the same time they hold well enough on the head. No discomfort at all. The construction itself seems well thought-out with some swivel so they adapt to the head shape when on.
The bad
While the earpads and clamp force are great, the headband is another story entirely. I could comfortably wear the D1 for up to 30 minutes, after which the headband started causing serious pain and burning sensation as it was pressing into my skull. While it may appear that the headband is padded, it's actually not soft at all. I guess the priority here was longevity but on my head it just doesn't work. Even with a full head of hair wearing them more than 1 hour was very painful.
But the biggest problem comes in an invisible, sneaky form: a heavy, smokey, burned odor. If you ever experienced the aftermath of a burned down building or a devastating fire, you can imagine what the D1 smells like. The odor is pervasive. Even after intensively airing the D1 out for almost two weeks prior to testing, I still couldn't deal with the smell very well. At first I could take it but after a few days of exposure I couldn't stand it anymore. I got nauseous and had to take them off. What an oversight. I don't think it's unreasonable to ask not to become physically ill from wearing headphones.
The ugly
The accessories included are subpar. You get a great looking hard shell case. Too bad it smells like it was hand-delivered by Satan himself straight from the depths of Hell. Other than that you get an unbalanced braided cable terminated in 3.5 mm with a 6.3 mm screw-in adapter. The actual 3.5 mm connector came undone the first time I went to unscrew the adapter. The cable costs 118€ on HEDD website. Let me just say it's not a 118€ kind of cable.
D1 vs HD600 sound comparison
There is no contest here. When compared to the D1, HD600 sound thin, with little body and weight, lack precision and sound very narrow. Their highs sound plasticky, unrefined, weak and powerless. As for the bass region, there is very little quality to speak of. When directly compared to the D1, the HD600 don't stand a chance. The D1 have vastly superior timbre, with realistic upper end, making instruments sound very real and alive. This type of sound is just out of HD600's league. D1's bass is so refined I couldn't believe my ears every time I heard it in action. Midrange and vocals are clean, with plenty of controlled energy, precision and they're reproduced in the mix in perfect proportion. HD600 amplifies vocals, as a result they stand out more but throw out the balance of the mix. Surprisingly, the HD600's vocals are actually colored, which D1 revealed only too easily.
HD600 stood the test of time and for a good reason. On its own they're great value for the sonic realism they provide. But they're no match for the D1. The D1 cost twice as much though. Do they have twice the sound quality? Yes, they do.
Final thoughts
I'm heartbroken about returning the D1. They are exactly what I wanted: a more refined, energetic, well-rounded and substantial HD600 with at least as good timbre. Little did I know just how superior in every aspect the D1 are.
As dumb as it may seem, the only real reason I returned them was that awful smell. I planned on getting a custom built balanced cable anyway and would probably get a Capra strap for the headband. These weren't deal-breakers. But causing such physical discomfort as that darn awful stench did to me is a step too far. I may be too sensitive, but I still don't think it should get past inspection or quality control in a product that costs so much, even if it's only a "budget" offering within the company's portfolio. Regardless, it's supposed to be a German-made product that is aimed at professionals and enthusiasts who use headphones for extensive periods directly on their head, and whether it costs 700, 70 or 7 €, some standards should always be upheld. Still, HEDD made an incredibly sounding headphone for a relatively affordable price. Even though their quality control is disappointing I would buy the D1 again in a heartbeat if new units came without the horrendous odor.
