Be cool if you list the songs that sounded horrible to see if I can reproduce.

Did you experiment with/without the tuning filters? Do you have some other headphones that you could compare them to?

Perhaps a faulty piece. You could email Dan, and talk about your concern; he is pretty good with email. From my demo, they sounded great, and I'm looking forward to getting them now.

@swapheadfi No, it wasn't a defective unit. I asked them if the unit I returned is faulty, they told me that it isn't.

These are actually extremely dynamic. But also extremely power hungry, if you don't have an amp that can push enough current to even the bass with the mids, they will sound exactly like you describe 'em. Problem is it really depends on the output device. My calss D laptop output is actually really decent with these. Also these are more like ear speakers and not headphones: play 'em loud or go home (currently using a Burson Soloist, class A 4W at 16 Ohms, the iFi Pro iDSD has also 4W but only from the balanced output)

I totally agree with @roskodan
The Aeon's are power hungry and scale with stronger amps. I drive them with a Lake People G109 which works great for me: Great heights and better separation of sound than any other headphones I tried so far. On the other side, I was quite disappointed when powering them with a PC soundcard, Dragonfly Red or some other portable amp from a friend.

Dan Clark has launched a re-tuned version that has boasted bass and treble. Who is the first to review them at head-fi? I am very curious!

@MalinYamato The Aeon 2 ? I briefly heard that too. Not better than the first gen, maybe even worse.

After further comparison with other headphones, I guess I narrowed down the issue some folks have with them feeling "compressed". It's the presentation, more forward sounding. As in macrodynamics getting precedence over microdynamics. I like it, as a complement to my other dynamic coil headphones' presentation. What I found undereported by reviewers is the obvious lean character of the o.g. AFC, and the hotter sibilance in the o.g. AFO. I also heard from trusted ears the the new generation is nothing to talk about vs the originals. But, hey, the old hype is dead, long live the new hype, right?