I ended up ordering a danacable lazuli reference for the 1266. Am hoping it will mellow down the highs a bit. I loved the utopia with the lazuli reference.
When I tried the Lazuli Reference, I found it made most of its effect in the midrange area, providing a warmer, meatier sound. Treble was silkier with the DHC Prion4, which provided a tighter bass and the most transparent presentation I have heard out of the AB-1266. I ended up getting the Prion4.
https://www.head-fi.org/threads/the...ressions-thread.666765/page-444#post-14261937
Later on, I decided to try the Superconductor which brought me to sell the Prion4, as the SC gave me the best of both worlds (warmth / transparency).
https://www.head-fi.org/threads/the...ressions-thread.666765/page-510#post-14797813
The more music I listen to with the 1266s... The more flaws are noticed... Bummer.
The AB-1266 TC are pretty ruthless when it comes to expose recording flaws, actually.
In my case, while I still consider the AB-1266 Phi TC a brighter-than-neutral headphone (less so than the CC, much less so than the original), I have found that investing in the source (adding the M Scaler to the DAVE), then in RF noise reduction (OPTO DX, battery powered equipment), and finally in better DAC and streamer power cables and interconnects has paid significant dividends.
I recently auditioned the Susvara and SR1a and - once fixed the source issues - I found the TC nearly as smooth in the treble as these two.
I am enjoying most of my music collection with little to no listening fatigue or treble quirks (e.g. sibilance) now, and rewarded by all those unique things the AB-1266 is so good at in the same time.
Of course, problematic recordings still sound … problematic
A complementary headphone like some Audeze or ZMF offerings could be a good investment for a more relaxed, midrange-centric and forgiving listening experience, when in the mood for it, or when the recording itself calls for it.
Another option is to look into power amp matching (tubes or warmer-than-neutral SS). Best pairing I tried so far in terms of tone and timbre is with the Riviera AIC-10.
As a last resort, there is EQ, but personally I have never been able to really fix a specific area of the sound presentation without affecting for the worse the overall sound signature and / or the transparency of the AB-1266, but this is possibly due to my lack of skill in doing EQ properly.