Just received my Heir 3.Ai earlier today. I have been enjoying them, but not sure if I like them more than my Pana HJE-900.
I'm not really experienced with reviews and am not versed enough in this stuff to make a true review or even give impressions that I'd want others to base a purchase from. However, I can at least give my thoughts. I've been listening to the Panasonic HJE 900 recently as well as the Shure SE215 and the Ultrasone Pro 900. I have found that the HJE 900 is very much to my liking. They were harsh to my ears at first, but I switched the tips to some UE foams and all of the treble harshness went away. I felt like the mids were brought forward a bit as well, and bass made a nice appearance to round it all off nicely for my tastes. Upon receiving the 3.Ai earlier today, I gave an initial listen with a variety of music in my library. Initial impressions were that the treble is indeed a tad harsh and a bit sibilant as others have mentioned. Mids were very nice however, and bass was nice and present, but not overbearing in my opinion (I do like my bass served up nice and thick
). Based on my experience with tip tolling on the HJE 900, I decided to try the same thing with the 3.Ai. To my delight, the treble has been tamed quite a bit, but retains detail, midrange is present, but not forward by any means. Bass seems to be improved in depth and extension.
I really like the Shure olives, and hope I can get some to fit these and the Panasonics after some modification. I think they bring out the best in some of the brighter IEMs (for me). I'm not sure what it is about the silicones that make the sound worse for me. I've never had a problem with them before on all of my previous IEMs, but I don't think they were nearly as resolving as my more recent sets (except the Shures).
Some basic comparisons to help others who have heard similar equipment (SE215, Pro 900, HJE 900):
Compared to the SE215, these have significantly more bass. Midrange on both is relatively comparable in terms of levels, but I'd say the Shures feel warmer in general which is a plus for me. They seem to have more life there than the 3.Ai. Treble is far more extended and present with the 3.Ai, but that makes them a bit more fatiguing to me for long sessions. The Shures stay with me constantly because they are just so comfortable to wear and I can listen to them for hours on end without feeling fatigued. I do wonder what the higher end Shure models sound like in comparison. I'd love to have something similar, but even better all around (especially up top) while retaining the bass response of the SE215.
Compared to the Ultrasone Pro 900, these are so much more well-rounded. Bass on the Pro 900 is incredible as most are aware of. The 3.Ai simply do not compare here, but that is likely a good thing for many head-fiers. I don't think I really even need to make more comparisons in this range. Midrange is far more present with the 3.Ai and that is very welcome to my ears. Treble with the 3.Ai is not as harsh as with the Pro 900 (not fully broken in!) even with the silicone tips. With foams, it is entirely tolerable for me and I'm relatively sensitive to sibilance, etc.
Compared to the Panasonic HJE 900... there is just something special about these Panas. I'm not sure what it is yet, but I'll attempt to describe after some more A/B-ing. They are incredibly sparkly, yet smooth-sounding in the treble. I think the 3.Ai have them beat on resolution up top, but the Panas are just a tad easier to listen to for me. I'd say the 3.Ai has the HJE 900 beat in the midrange for clarity as well, but the Panasonics are still relatively warm and pleasing with enough presence for me. I wouldn't mind a little more body to the midrange, but I can't complain about what they have to serve up. As far as bass is concerned, I also feel like I need more time comparing the two. My thoughts for now are that the 3.Ai goes lower with more extension, but the Panasonics seem to attack kick drums in a very satisfying way, that the 3.Ai could not replicate. This is my first experience with balanced armatures, so maybe this is just a downfall inherent to them that I was not aware of. Overall, I need more time to decide which I prefer. I'm not sure why, but the Panasonics just do everything very well for me.
Sorry I have no comments on soundstage. I just don't feel comfortable commenting there yet because I need more experience comparing this aspect of the sound and I need to do a lot more critical listening to all of my headphones.