KR Audio KT88 Vacuum Tubes

@bojack ,it is a sadddd fact that in this day & age,many people have more $ than brains!

I think it depends on “how good” your amp is, as well as the rest of your system whether you’d experience any sonic benefit.  If you’ve got a super high end single ended with no negative feedback, like Japanese Audio Note, French Jadis, VAT or PP McIntosh and the rest of your system is equal, I think you’d like the KR Audio tubes.  If a “lesser” amp, like Line Magnetic, or Willsenton, not so much. The last two are not bad amps, but run negative feedback to reduce distortion and  mutes some of the second order harmonics which makes tube rolling less impactful. 
 

I don’t know about the KT 88, but I have a Cary Audio 300SEI LX-20 that is designed for the KR 300B XLS which puts 550 volts on the plate with 55w dissipation and 20w output. The Cary will eat normal 300b’s like a six year old eats through Frosted Flakes! The KR XLS in the Cary are fantastic, Deep, tight impactful bass, something normally missing from 300b. The midrange is simply heaven on male and female vocals, acoustic guitar and strings. The treble is clear, clean and very articulate.  

I have a Willsenton R800i 845 with Gold Lion 300b in front of Shuguang 845B output tubes. Both significant upgrades over stock Linlai hifi series tubes. Would I swap out the Gold Lions for KR 300b? No, probably not. I don’t think the $$ value equation would be there.

I also have a Dennis Had Inspire KT-88 that came with Gold Lion as stock. It will also run 6L6, EL34, and 6550. The Gold Lion KT-88 is the most balanced, linear and musical tube I’ve heard in the Inspire. It’s a simple SEP design with one 6SN7 or 6SL7 as the signal splitter and driver in front of the output tubes, no negative feedback, and hand built point to point wiring. It was only $2,000. Would I roll in KR KT-88s at $900/pair? Maybe, if I won the lottery! 
 

Bottom line, I’ve had good experiences with the Gold Lion series of power tubes, definitely a fan. Do I think the KR tubes are an upgrade worth the cost? Absolutely! If your pocketbook and system can handle them. 

No experience  with the kr tubes but I have gold lions and sohpia electric  tubes the sohpia  blue bottle kt88s are a step above the gold lions. 

My amplifier is a Conrad Johnson ART27a class A producing 36wpc.  For the benefit of the first three respondents who have not heard the KR tubes, the amplifier lists for $22K.  The pre-amp is C-J's ART88 at $28K.  All pretty high end sound producers.

My interconnects cost several times what a set of the KR's would run and the speaker cables sell of about what the amplifier does.  So I'm willing to spend $1300 for a set of four if they truly sound better than the Gold Lions. I just re-tubed the amp's KT88s after about two years of use for about $400.  I buy tubes from reputable sellers or C-J, never on Amazon or eBay where the lower quality tubes end up.  I'm told New Sensor separates out their best testing tubes and they become the Gold Lions.  

As for the Sophia Electrics, I understand they don't manufacture their own tubes either, they come from Shantung in China.  But they are again some of the better testing valves from that company.  Rather the Gold Lions of Shantung and pretty also.

Thanks to trivema and retiredfarmer, thanks for your input; very helpful.  Tubes are a maintenance issue, especially in a circuit like this one which drives them hard to produce that much class A sound. At worst case the KR Audio tubes will likely last longer and the current Gold Lions will become backup for the next replacement cycle.

Still, don't need power tubes right now... unless they really sound better.

I am one of the dealers for KR and have had them in my own Art Audio Opus 4s. They have the same power output as a typical KT88 but the plate dissipation of a KT120.  They will last longer.  This is the same recipe KR used on their 300Bs.  Plate dissipation is 50w vs. standard Western Electric Spec of 40w.  

In practice, they are more linear. "Better" top end and tighter bottom end.  This means tighter bass response but also means a brighter presentation which is why better is in quotes.  In my system I found them to be too bright and shifted to a different tube compliment.  My amps also accept KT120s and I opted for those to get just the right tonal balance I was looking for.  If you are looking for more top end energy and tighter bass, they are incredible.  If you are happy with the Gold Lions tonal profile, move on.