WOW! Installed the Gen 2 .1uF Sonicaps I purchased from Danny on his recommendation in the Alpha XOs. The tiny bit of sibilance that remained is no more. Smooth as glass in the lower treble. Gained detail without the annoyance that more detail can bring...only the wow factor.
The overall balance of the speaker seems improved and what was a seemless XO to begin with is now non existent. I hear a touch of warmth that makes the speaker even more enjoyable over the long listening session. Not coloration just a more relaxed and natrual presentation. I found this to be the case with either solid state or valves.
Thanks Danny for futher refining a great speaker. I am curious if this is what you intended.