Preamp Sibilance?

@ghdprentice - I appreciate your advice. Before I swapped to the duelund cables I was using Cardas Reflection interconnects. They really made a positive difference in the warmth they brought to my prior speakers. I sold them when I swapped to the Duelund cables for my current speakers, which are naturally warmer. I will definitely consider going back if I ultimately need to. 
 

@bolong - I’m currently using EML 45s rectified by Sophia Electric Aqua II. I’ve never tried anything other than the EML 45s but I have swapped rectifiers. Interestingly I tried this after my original post using PSVANE 274b in place of the SE. that did in fact help with the Sibilance problem quite a bit; but the tradeoff was a darker, less airy, and harder sound that was less preferable overall to me (except for the Sibilance problem). 

Once I get another couple of hundred hours on the system, I’ll swap the PSVANE in again for a more fair comparison in a fully broken in system. 
 

Were the Telefunken tubes ever swapped out?

Glad to hear things are getting better. If you end up really happy with a touch of hardness, then you might be able to get some Cardas interconnects. They are slightly warm and can tame a small amount of hardness. 

Update for all who are interested.

been leaving the preamp break-in in my second system (solid state) pretty much 24x7 since my original post. 
 

Tested once during the week with a definite improvement in Sibilance but still some hardness / harshness to the sound.

then back to breakin for another 100 hours and back in my main system today. Wow, how nice it is. Sibilance mostly gone, harshness gone, left with nice full transparent detail. 

I can tell you all I wasn’t confident it would play out this way. Let’s see if some more hours bring more pleasant changes. 
thank you again!

@sls883 @audioman58 thank you for the LTA suggestion. I listened to them at LTA in DC a few years back and was very impressed. With this latest purchase I was shooting for the equivalent to no preamp so I could add a new TT, so I tried to stay lower cost in the pre (but still not low). And the Serene has gotten glowing reviews from many reviewer with virtually no one dissenting. If some of these options don’t pan out; I may be back to the LTA option or similar. 
I’d love to hear my gear with @ghdprentice Audio Research but I’m not seeing that happening any time soon. 
also, it’s nice hearing I’m not the only one who has experienced that with a pre.

@audioman58 +1.  I had a sibilance issue with my previous preamp and I kept blaming it on the recordings.  It developed issues and I ended up getting a LTA MicroZOTL level 2 preamp.  My problem went away.  I've done a fair amount of tube swapping and have found a combination that I really like. 

If you want a great preamp that checks all the boxes the Linear TubevAudio

micro Z-OTL. Is a great preamp and you have up to 4 tube types and characters  to choose from , great parts quality throughout.  David Berning design ,

then LTA worked to make this current  model even better ,

 passive preamp sections or Using alps,Bourne type pots you loose tons of detail 

a resistive ladder,relay type is optimum , I am using Rays select 6sn7; tubes

and top Medical grade Telefunken 12au7 tubes  Hifi tuning supreme fuses , even feet make a difference the isoacoustic Bronze are a great value.

and excellent AQ Tornado source power cord , it’s a exceptional preamp for around $8k with power cord and tubes can go toe to toe with preamps much more expensive that in our audio circle have compared them with. It’s a Essential part of the Audio chain to  voice  and control Everything to your Loudspeakers.

@ghdprentice - Thank you. I've seen you say this many times before in many situations and I will definitely give it some more time and track progress.

@bolong -  Thank you for the fuse suggestion and recommendation. I hope I dont have to go down the fuse route to solve this problem but I may give that a shot if other options don't work. The reviews I looked up seemed very favorable.  

@yyzsantabarbara I appreciate sharing your experience.

Like the man said, give the Serene another 100 hours. I put an Audio Magic M2 fuse in mine also - a fuse that has a marvelous way with treble excess.

I owned the Holo Serene KTE for about 2 to 3 years and sold it a few weeks ago. I liked it a lot, but it went down the totem pole in stature for me when I took it to my friend's place and compared it to his hand built pre. His pre was just a stop gap unit to test the open baffle speakers he is creating. His pre was so much more transparent than the Serene. I was shocked and disappointed.

However, I never heard any sibilance on the Serene when it was hooked up to my CODA #16 amp and Yamaha NS5000 speakers. It was a little warm and I was not sure if that was the best sound for my tastes. These questions only came about after hearing my friend's preamp. So, for my experience sibilance is the last thing I would say about the Serene.

I now use the Benchmark HPA4 (same as the LA4) in place of the Serene. I realized that I like the extra bit of clarity I get with this setup. Again, no sibilance with the setup either.

FYI, I ended up replacing the Serene with the $799 Schitt Kara F preamp. Which also allowed me to sell the Schitt Mjolnir v3 preamp. I sold it yesterday and that is a very warm Class preamp + headphone amp. 

I would not say the Kara is better than the Serene, but I like how it sounds on my RAAL SR1a earphones + Schitt Aegir v1 amp and also Magnepan Mini speakers + Schitt Wotan amp. I tried the Serene in this setup before and it was very good, but the Kara is preferred. The Serene is more transparent though the Kara is pretty good there too.

Well, definitely start with breaking. Get 200 hours in and note the improvement. If that gets you close, then more. My equipment needs over 600 hours for full breakin.