Really curious to hear more on these...also does anyone know what the connector on the cable is like? Doesn't look like HD25/Amperior cables will be compatible but I'm curious about getting a mic on a pair of these. Hoping they can be the portable counterpart to my DT770.
My HD25-1s from 2005 were recently stolen along with the rest of my luggage and so I've just got a pair of HD-26 Pros - 4 hours ago. So very much first impressions. They do not just sound like HD-25s. I'd say much more precision, especially in the treble and a more open soundstage. Very nice so far...
Update: I have now clocked well over 100 hours on the HD 26 Pro headphones and my initial impressions regarding the sound quality compared to the HD 25's remains positive. It should be noted that my listening on the HD 25's have been with the velour pads. This may contribute to some of the differences in the bass and lower midrange*.
Below I will try to describe some of the audible differences and how they manifest themselves to my ears - not necessarily to yours.
Low level details are presented much more convincingly and evenly through the whole frequency range on the HD 26. The HD 25 in comparison seems to truncate the finest details. This is clearly audible on well recorded acoustic music where the HD 26 has better instrument separation and presence, longer transient decay and more spatial information. This in turn makes the soundstage wider and much deeper on the HD 26.
The difference between low bitrate compressed formats and lossless formats are easier to hear on the HD 26.
High frequencies are better balanced and less splashy on the HD 26. Cymbals now (compared to the HD 25) gain more shimmer and inner detail and move a bit back in the soundstage so that they are actually perceived as being a part of the drum kit and not standing on the front edge of the stage. Sibilance is also less spitty and more natural sounding. Treble presence and extension is still excellent though.
I find the midrange clarity better on the HD 26. *Vocals are less nasal, more articulate and background vocals and instruments are easier to separate. Lower midrange has more body AND overall midrange detail is increased to my ears. The soundstage is less compressed and there is more space around voices and instruments giving a greater sence of intimacy and transparency.
I did not find the HD 25 to have much of a midbass hump with the velour pads. Things might be different with the pleather pads. I do find that the overall amount of bass is similar between the two models but that the HD 26 reaches lower with less compression.
The HD 26 is not as demonstratively transient happy as the HD 25. It is more even sounding and dynamically expansive though.
I can see why some people would prefer the more aggressive sounding HD 25 for some applications. For monitoring and general listening I do find that the HD 26 is both more natural, accurate, resolving and easy on the ears at the same time. This, for the record, is NOT a contradiction in my book. It tells you more about the recording than the HD 25 does, but it does not smack you in the face with bright and sibilant recordings the way the HD 25 does.
Take everything above with a grain of salt. I have been known to be wrong...... - Once in 1987 and then again in 2004 I believe
Better than HD 25. On my ears it's borderline iem territory! One thing though: Because of the softer and slightly larger ear pads, the surface area touching the ears is bigger and the headphones can get hot and sticky. I would like to see Sennheiser make a velour version of the pads.
They are very good. Now after some more listening all I could wish for is a bit tighter bass. I like my bass tight as a Camels ... in a sandstorm. I'm borrowing a friend's NAD Viso hp50 at the moment and they are quite a bit more controlled in the bass department than the HD 26.