Zu Omen or Tekton Lore

Read a little up stream,I have used the same configuration with several pairs of speakers and had no sibilance.
I was fortunate a few years ago to be able to compare some of the most expensive cables of the time and even Audio Note Sogon made only a subtle difference at best and the gear used was worth more than my house several times over.
It is funny that using lab grade test equipment has never measured a difference in the frequency response from one interconnect or another as long as they are constructed correctly.And if you can show me different i'm open but interconnects and power cords are not magic wires.
Although I have all silver in teflon speaker cables,inter connects and PS audio 8 and 10 Awg. power cords.
Capacitors do however make a measurable difference up to a couple of DB. in some frequencys. I will not go into an endless cable debate.Sibilance lives in the 8khz. range and if the big new cap I put in peeks in the upper mids where the tweeter peeks to 101.5 db. output around 8khz. I very well could be over 103db! at a very sensitive frequency.
I am pretty sure of the problem and I'm just awaiting parts.
Did you look at the graph of the tweeter response?
If no one else has sharp SSS and TTT it would almost be a act of God looking at the steep climb of the tweeter it's self.The caps used nearly need to have a recessed upper mid range just to control the top end of the female voice.
Eric did a great job of balancing this tight rope but upgrading caps can upset the apple cart.
I would leave the Lores alone unless you are willing to stay in it for the long run.There is more detail to be found in the top end (sizzle) but the proper balance is critical and may not be cheap.I am willing to roll as menny caps as it takes.
I am all ready upgrading resistors,Mills and possibly Mundorf,Audison internal cable ect...

I agree John,
No sibilance at all with the Lores or Pendragons in my system. They are the least fatiguing speakers I have ever owned or heard and I have a very sensitive ear due to Tinnitus.
It has taken me a while to understand the concept of synergy, which in my mind means that as I change one component, I.e. speakers I may have to change the associated cables, amp, Pre amp etc to maximize the end result, which for me is that golden magical moment. It has nothing to do with a measurement for me, but just trusting my own hearing and a lot, I mean a lot of trial and error.
I too have never put much effort into my cables, but am now opening up to that possibility. I have nice quality cables now, but I have not A/B tested any in the past. However with highly sensitive speakers, and in a 100 year old Victorian building, I have found power conditioning to be of the utmost importance. I use an UberBuss and love it. I have also spent a lot of time, energy and money to match amp, Pre-amp, and DAC with my room and my speakers. There are so many variables in any system that the tweaks are limitless! From speaker positioning, to cables, etc. etc....
I am curious about the effects of Capacitor changes on the Tektons, and I even discussed options with Eric as he was building a pair for me, but I decided to wait due to the cost, and in the end I did not feel the need to change anything.

I agree ZMan...

One of the problems was due to my positioning,I tipped them back,Eric said that would spike the tweeter by as much as 3 db. After leveling them it helped alot.
The other issue is with a bright pair of caps soon to be swapped. I am not blaming anyone for the sibilance and I'm surprised no one else has made a capacitor upgrade and chased these issues already. My advise would be to use very neutral caps Clarity cap,Ansar,Daton,Solon as any peak in the upper mids creates a problem.

Wow! since leveling them and letting them run in some more from sun up to sun down over the weekend and for 2 hours I ran the volume at 12:00! somewhere around 10 watts!
Suddenly the high end went flat so I removed the resistor I added to the tweeter to drop the spike by 2 db. and still no glare,seems the new caps smoothed out and the sibilance just vanished as fast as it came.They got another 38 hours just since last week end of break in time.So now I have more caps coming,they can just sit,no more cap rolling!
All I am going to do now is go in and remove the Xovers and clean everything up,replace the resistors with Mills non inductance and there done!
In the end it will all be worth the trouble but one piece of advice is be very careful to select neutral capacitors and give them some time to smooth out. Mine took close to 90 hours.
Funny thing is when I first put them in no sibilance but they went through a 50 hour or so stage where you couldn't stand them,I seriously hope this is it and they are done with no more surprises! This is the most radical burn in I have ever encountered,although I did have a similar issue with clarity cap SA a few years back as they lost the top end for a while and suddenly it emerged after a couple weeks of use. So I guess I shouldn't be to shocked.