I just wanted to post a couple impressions - I usually lurk, so don't have much experience with this, but maybe I can help people who might be on the fence. I received the Buydig refurbished A900x last week, as well as the AKG K167 Tiesto. I let them burn in a few days, listening intermittently. Tonight I listened in depth, using my modified Fostex T40rp mkII as my baseline. My system is Windows lossless (or Oppo 83) - Squeezebox Touch - Benchmark DAC1. I listened to the K167 with both stock pads and the Shure 750 pads.
I appreciated the form factor on the K167, they are lower profile, and isolate better than the other two cans. They are more comfortable and lighter than the Fostex with the headband modification. The Shure pads are warm, but very comfortable. The A900x wants to slip down and I find myself adjusting them more frequently. My ears don't touch the drivers on the A900x however, as they do with the stock pads on the K167. I don't have big ears. Construction on the A900x seems better to me, but they are not very transportable.
As far as sound is concerned, bass is strong and full on most music. Some genres however (just got the Jose James album - R&B, jazz) had too much bass, and it can overpower and bleed into the mids. Most of the music I listened to did not have that much bass, so I really enjoyed it. The K167 had pretty nice bass and sub-bass. It is better controlled and layered but lesser in quantity than the A900x. In the future I would like to hook up my Audio-GD Roc amp to see if there is improvement in control of the A900x bass. Impact on bass and mid-bass was better on the K167, even if low-mids and mid bass were low. In comparison, my Fostex don't have as much low bass as either the K167 or the A900x. Also, the Fostex has some low mid bloom which can get busy.
I found the A900x to have a very smooth midrange and treble. I don't hear any peaks in either. The mids are almost as full, fleshy and palpable as they are on the Fostex. I feel that the treble is presented well, with some mild roll-off, in both the Fostex and A900x. Well recorded female voices put me in that wow space with both cans. Neither have any sibilance. Texture and air are great on both. Transients on both the K167 and A900x are great. Mids are thin on the k167 in comparison.
Treble on the K167 was its downfall. There may be a peak in the treble with some upper mid suck out that made things sound metallic. In busy passages, some instruments would pop out in the peak range that were distracting and unnatural (Ceu - self titled album). Sibilance was present and uncomfortable.
I would say that imaging is better on the A900x than the K167, and much better than on the Fostex. I didn't hear much difference using stock pads or the Shure 750 pads on the K167, but I was only listening for differences in the sibilance/peaky treble.
I am keeping the A900x, but the K167 is going back, or getting gifted (lucky sister). I'm not sure if the Fostex or the A900x is my favorite yet, but I can use both. I wish I could find a more transportable option in a closed circumaural can, and I may try out the Fischer FA-003 or one of its rebrands soon. I will probably stay away from the K550 based on what I have read. Any other suggestions? Beyer DT660?
Making decisions is hard
