My listening impressions on the prototype of the HEDDphone, all HiRes audiofiles (24 bit/ 88.2 - 192 kHz):
1. Comfort level ... (not really about listening yet...): The drivers are very massive and heavy. The AMT drivers were developed from loudspeaker tweeters and need a very strong magnetic field.
On the prototype the headband was padded with a very thick layer of foam and encased with leather. I wore the phones for two hours on my head and it was okay. But that still needs some work...
I suggested to try out a suspension headband and the engineer confirmed that more R&D is going into the construction of the headband.
The weight of the drivers is a given factor for now, so these will be heavy headphones.
2. The prototype was driven single-ended by a Lehmann Audio Linear headphone amp. My impression is that this set-up was a bit limiting, these cans really need a lot of power/current to show their full potential.
HEDD Audio is considering to offer balanced cables as well and will do some R&D with balanced / fully symmetrical amplification in the near future.
3. Soundstaging / Imaging: In one word .... very natural. The soundstage was wide and deep. I didn't miss anything in this respect. I use a Hifiman HE-1000 SE and a Beyerdynamic T1 at home, so I really am a fan of a big, wide soundstage
and really dislike Focal headphones for their in-head presentation. In short the HEDDphone prototype did very well in soundstaging, I listened to big classical orchestra works like Holst - the Planets or Stravinsky - Firebird Suite and was very satisfied.
4. Tonal balance: Very neutral, well balanced. There wasn't any part of the frequency spectrum that stood out, no audible spikes. A very clean and refined sound in general.
5. Highs and resolution: Very detailed, refined, lots of resolution, one of the best highs I've heard in a headphone. No sibilants, no sharpness, not overly bright like the HD800 (S), just the right amount of detail.
That's one of the specialties of the AMT driver, resolution without any kind of sharpness or sibilance.
6. Male and Female Voices: I listened to Anna Netrebko (Dvorak-Rusalka, Donizetti-Lucia Di Lammermoor), Cassandra Wilson, Diana Krall - The look of love, Billy Joel - In a sentimental mood / Captain Jack, Sting, Carl Orff - Carmina Burana ...
All voices sounded very natural, full bodied, a real pleasure.
7. What about the bass? The prototype had a very tight and well textured bass, a little more amount of bass than the HD800S for comparison. But it didn't have the weight and slam of high end mangneto-planars like the Hifiman HE-1000 SE or the Audeze LCD 4Z.
I heard a slight emphasis around 60-100 Hz and below 40 Hz the sub bass / deep bass was rolled off. I listened to titles with a lot of deep bass like Daft Punk - Get lucky, Café Drechsler - And now Boogie,
Donald Fagen - Morph the Cat, deep organ notes as in Bach - Toccata und Fuge in d-moll, the Drumset in AYA-Authentic Audio check ... and something was missing.
The slight bass emphasis at 60-100 Hz worked very well with titles like Nirvana - Smells like teen spirit, Calexico - Feast of wire or the bongos in Santana - Africa speaks though.
With classical works the punch of timbals like in Stravinsky's Firebird Suite - The infernal dance of the Kachschei's subjects wasn't quite there.
I spoke about my impressions on the bass reproduction with the engineer and the product manager of HEDD Audio and they both confirmed that they are still working on the deep bass reproduction in R&D
and have some innovative new ideas to improve this frequency section but are also well aware that high-end magneto-planar headphones have more deep bass extension in comparison up to now.
A fully balanced/symmetrical amp might have provided more power and current, a single-ended / asymmetrical set-up (like the Lehmann Linear in my listening session) might be another limiting factor ...
8. What about the speed of the drivers, transients ? I'd say quite fast, faster than most dynamic headphones. See above ... a fully symmetrical amp might provide even more speed.
Of course this is highly subjective, but my impression is that my Hifiman HE-1000 SE is still the faster headphone ....
The team at HEDD Audio is especially proud about their AMT drivers and in theory these drivers should have an advantage over many other driver technologies in this respect ....
Being a German company their main goal was to surpass the reference headphone in the 1500-2000 Euro area and that is (at least in Germany) the Sennheiser HD800 S.
There are other contenders like the Hifiman Arya in this price range but Hifiman is rather a niche-product in Germany.
I know the Sennheiser HD800 (S) quite well and in my opinion HEDD Audio will achieve their goal and offer a headphone that will sound better than the HD800 S in most respects.
So far HEDD Audio is not quite in the game for the very TOTL headphones that cost more than 3000$ /Euros but who knows what comes next ....
Please feel free to ask further questions.