Listening to my reference classical recording:
Baltimore Symphony Orchestra: David Zinman conducting Copland's Rodeo, Billy the Kid, and various works.
This is near heavenly. The tiny details the HE-6 picks up I never heard with the HD600 is surprising. The sound is like I am standing on the podium and I'm surrounded by real instruments. The textures, timbres, and dynamics are simply breathtaking. This is, with absolutely certainty, the best headphone I've ever listened to.
Where the 'near' part kicks in is in the soundstage and imaging, which I've mentioned before but I thought I would go into more detail about it. First a bit of back story, though. For the last 8 years I've been a listener of HD580 and HD600. I would characterize the soundstage and imaging of these near identical phones as medium in size, and very good, but not excellent, respectively. The soundstage reminds me of a 100 seat recital hall, and the imaging is precise in all points, but does tend to be slightly on the 2 dimensional side, meaning the sounds are lined up in a straight line across your listening vision.
The HE-6 is a larger sound stage, by a good bit, but not as large as HD800 or K1000. Generally the sound stage is excellent, but my problem with it is when it reaches towards the center it feels like it goes forever deep without an end. The sound just falls into a black hole and never comes back. To illustrate my point, I drew up a fabulous MS Paint demonstration:
This ties directly into the other part of my complaint, the imaging. When I listen to the HE-6 I hear precision placement from approximately 8 o'clock to 10:30-11 o'clock on the left side, then another void until you reach around to 1:00-1:30 o'clock down to 4 o'clock on the right. Here's another great MS Paint to demonstrate:
In listening to this orchestral CD, which I believe to be one of the best recorded, ever, I can hear the first violins directly to my left very close, with some of the second violins and the left edge of the percussion section in very well defined locations. Continuing around the arc, the rest of the second violins, the entirety of the woodwind section and most of the brass section, and the viola section is completely without form or location. The sound is just there without origin. Moving on, we find the right edge of the brass section with the trumpets, tuba, and some of the trombones fairly well defined. Directly to my right and close is the cellos, so accurate I could reach out and touch them, and behind them is the line of basses, audibly in a row, just like they are in a performance. When I listen to this CD on my HD600, I can locate each instrument without problem, but the extremely precise imaging of the HE-6 to the direct left and right is not present. The HD600 merely is good at locating everything, but not good enough to give me any of the indications that I am really standing there.
Now for the spoiler. Enter the $15 IEM from MEElectronics, the M9. This cheap thing is responsible for my not being entirely happy with the HE-6. The highs are god awful, the mids are even worse, and the bass is very much there, but not that clearly defined. It is a cheap headphone, after all. What this cheap thing does, however, that both the HD600 and HE-6 cannot even remotely come close to doing, is that it presents a truly 3D environment, immersing me in the sound as if I really were there. Precision imaging in all directions doesn't even begin to describe it. While the timbres and textures are quite bad, I can easily pick out where each instrument is around the entire arc, even picking out individual instruments in each section. Where I'm going with this is that I'm assuming a high end IEM will be able to recreate this 3D environment, but with proper detail and timbre to make believable versions of these instruments. I have never heard such a 3D environment before, from any full size headphone I've auditioned, including but not limited to: K1000, HD800, HE60, O2MK2, D7000, HE-5LE, SR-202, SR-404, K701, and the list goes on, and yes I did include the K1000. With such a roster of phones, I am inclined to believe a true 3D environment cannot be created by a full size headphone, even with angled drivers (HD800/K1000), or no ear cups (K1000). Even a good speaker setup does not put me in the music like these IEMs do. I also think these problems will not improve with speaker amp power as much as I wish they would.
Therefore, it is very likely I will be returning or selling my HE-6 to begin my IEM journey, of which I have no idea where I will start. If anyone knows of an HE-6 in IEM form please let me know! I am willing to spend as high as the UE18 which I believe is the priciest custom on the market at $1400, but also would love to find something cheaper that matches my criteria. I was happy with my HD600 rig for so long because it was so incredibly cheap for the performance. I'm not one who has to be the biggest spender to show off on the forums or at meets, so spending just to spend isn't my style.
In all other areas, I rate the HE-6 a perfect 10, but the soundstage and imaging problems kept them from being a keeper. These problems are worse and better than other full size headphones so to most people they will sound perfectly fine. My experience was unfortunately (or fortunately) ruined by a pair of disposable IEMs I bought to have on the run that I could step on by accident and not worry about replacing.
Thanks for reading.