Tube change.

I am not big on buying into Output Tubes, but have bought into such Tube Types recently as a result of having to.

I am with the Camp that believes the end of the signal being the betterment over what comes before is getting the wrong end of the stick.

The Sent Signal is everything, do ones best that they know how to, with the intent to provide what is to be met downstream the very best that is available within a constraint of a budget.

Small Input Tubes and Output Tunes in advance of any Power Amp Output Tube is where to focus the available funds. Only concern oneself about the Power Outputs when they are losing their MoJo and moved nearer the non-ideal spec's for the Valves.

Then if one wants to dent their coffer, why not money is needing to be spent, so why not on something that costs more, but comes with the notion, it is to be quite special. Hopefully all the other choices made, bring the true symbiotic relationship between the overall selection of Valves. 

Gold Lion KT88s here in C-Js best amps.  on my second set.  They recommend them.

Is your pre-amplifier tube or solid state? If it has any tubes i recommend focusing on those as they are the beginning of the food chain.

I upgraded older tubes on a preamplifier which had two tubes to Amperex Orange pq red tip. After making this change i did not feel there was a need to change out 16 power tubes on my monos.  these tubes were on the pricey side but a lot cheaper than replacing 16 Power tubes.  

As another owner of a Dennis Had amp (Inspire SEP Firebottle HO...high output!) I do sympathize with multi tube amp owners (owned a Jolida amp for a while that had 4 output tubes). I'm obligated to use efficient speakers but I like horns so it's FINE. The cool thing for me is my preamp uses 6SN7GTB tubes as well as the Had amp so various versions of those accumulate in my tube drawer as well as the Had power tube heap. I like Gold Lion stuff mostly and think their KT88s are great...as well as the 77s, 66s, 120s...you get the picture. It's almost too easy to take the 2 minutes or so roll 2 tubes (preamp tube is an Amperex that's likely a rebranded GE...NOS GEs are preferred in the preamp). I swap the Had with a Pass XA-25 when the mood strikes me so there's that.

Sophia Electric tubes sound like a great choice. Tell us what you think when you get them in a running. 

SE as a company has been quick to respond to questions. Yesterday’s reply from them was that with the amps I’m using I should expect a significant improvement in performance. We shall see. The designer of my preamp has a new upgrade for it and once thats done I will be moving towards purchasing the SE kt-88’s. I appreciate all the comments and input received on my posting. Thanks.

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I like Sophia electric tubes for the 6sn7. no experience  with Kt88

but generally, all tubes i got from Sophia electric tubes are good and reliable

I’m currently using Gold Lion Kt88’s. They aren’t bad sounding although I really have nothing to compare them to.

I have tube rolled KT88 tubes in a Rogue Cronus integrated amp. I was unaware of Sophia at the time. I tried JJ Blue, PSvane Horizon, and  Genelax Gold Lion. My conclusion was the Gold Lions were the most open , had extended bass and treble, and all round more musical than the other 2. 
 

I have since bought a Primaluna EVO 400 and replaced the Primaluna EL34s with Gold Lion KT88 with the same results.   Primaluna like Sophia tubes are made in China supposedly to their specifications and control. 
 

My experience may not be the same as yours and nobody is right or wrong. 
And my experience probably doesn’t matter anyway 

I agree with @jbsqg, the preamp tubes are 75% of the sound. I only changed power tubes after going all NOS preamp tubes in both the Rogue and Primaluna. 
 

@sidog1460 What KT-88’s are you running now? I have a little Dennis Had Inspire KT-88 that is a clean, simple design with only one 6SN7 or SL7 signal/driver tube.  The Inspire can run 6550, EL34, KT-66, -77, -88 and is very sensitive to tube rolling, I can distinguish subtle and not so subtle differences between tube models and brands.

It came with New Sensor Gold Lion KT-88’s, a clean, transparent, well balanced tube.  I purchased a set of Shuguang Nature KT-88-T and found them “darker” with more bass response, a bit more bite in the midrange and good extended treble.  They were only $65 ea. You may want to take a look at the Shuguang if you want to experiment a little without the investment SE’s would require for eight tubes.

@curiousjim When the TA Rhea and filter came out Tom Vu the designer allowed me to audition it at home and recommended listening to my music w amps plugged into the Rhea not into the wall. The Rhea was made to handle high voltage components and the noise floor dropped significantly(among other benefits) with the amps plugged in. Couldn’t imagine going back to plugging them into the wall.

Agreed. Nice looking amps... that's a lot of tubes. 

I have used a number of different Sophia tubes and they have sounded superb, warm natural and detailed. While they are not Takatsuki... they are upper tier. 

Wow! What beautiful amplifiers! Sorry that I thought that they might be VTL's as your's seem to be in another league altogether, at least compared to lower-end VTL's. So all I can say is keep playing with input tubes. Apologies for rambling on about the wrong amps.

@sidog1460 

You don’t have your amps plugged into your Rhea PC, do you?

I've had a few Sophia Electric tubes myself and they generally sound excellent. Their Blue Glass 6SN7 might be my absolute favorite.

@axpert I have the Triangleart mono’s mentioned above.

Triangleart L-200Mk 2 preamp + Rhea power conditioner 

Emm labs transport and dac, Trenner&Friedl Isis speakers

@jbsqg I have the Triangleart TA-350m mono’s. 8 Kt-88 tubes(can’t use 6550) 3- 6ns7 tubes driver 1-6sl7 rectifier tube. I was told the power tubes on the amps would make the biggest impact on sound quality. SE of course makes no guarantee but states customers report a significant improvement in almost every area musicality, soundstage, bass, midrange when using their tubes. Even though expensive considering it because it’s still less than upgrading to another amp and less hassle than trying to sell mines. I’m very pleased with my amp but this little voice inside me keeps saying What If?

Over the years, I have owned several "high end" tube-based amplifiers. With one exception, they have all been designed or optimized to run KT88's. Subsequently, I have spent a ton of money "rolling power tubes" as well as signal tubes. Currently, my tastes have taken me in a TOTALLY differently direction. Being a former classical musician, I strive to achieve the most realistic and musical reproduction from my system. 

To be quite frank with you, the KT88 tube has never quite satisfied my tastes, regardless of the amplifier in which they were used. I have tried almost every brand, including some very expensive NOS tubes. I have also tried CRYO treatment on several. All the results have been less than satisfying to me.

Now, you mention SOPHIA ELECTRIC. That is one company that I have not tried, though I have read several professional reviews and reports, which highly praise the SOPHIA ELECTRIC products. Especially, the EL34 and the KT88 as preforming at a much superior and musical level as anything else out there.

Eight SOPHIA matched tubes is a pretty big investment chunk.

Also, I have no idea what the rest of your system is comprised of. 

I would only caution, depending on your musical tastes, that the end result might not be as dynamic as you would like to anticipate. ESPECIALLY if your tastes run toward Heavy Metal, Rock, and the like. "CICO"!!

Using the SOPHIA tubes "MAY" yield subtle or more sophisticated improvements. All of which tend to be more evident if you tastes run in the direction of classical, jazz, or small ensemble music. 

SOMETHING TO THINK ABOUT.!

I agree with Bgross. I'm guessing that you have a pair of VTL 225 amplifiers. I have a VTL ST150 so it may use the same tubes as your's. If your amps take  6350 drivers make sure that they are still strong and balanced. There's not much to be gained in rolling this tube since they were all made by Sylvania as far as I know but the triodes need to be balanced to sound their best. The 12AT7 tube contributes most of the character of the amp. My favorite 12AT7 type input tube for the amp is a Brimar 4033. It, along with a Mullard 12AT7 are wonderful in the V1 position but I think that the Brimar has a significant edge in body and drive, especially when in Triode mode. Also, try playing (within reason) with bias to fine-tune the sound of the amps to your taste as they will respond well to changes of a few millivolts. If one or two tubes stray from their bias setting by 6 or 8 mV you will sense that something is off.  For the longest time I ran my amp in tetrode but after replacing the drivers it sounded fantastic in triode mode and I can't switch back.

My apologies if you don't have a VTL !

@bgross By the way I have changed out my preamp tubes to the SE tubes over a year ago. They made a small but noticeable difference.

@bgross I will look into that. Thanks for responding.

Small signal tubes make a bigger impact. Try rolling those 1st - it's a better starting point than 16 new SE power tubes, oof! Just my opinion 

@bolong. In some reviews of the SE kt-88 tubes reviewers have stated that it takes the amps sound and performance to a higher level. I can’t afford to upgrade to another amp but if buying new tubes can come close to giving me a little or a lot more of what I’m looking  for that would be worth the price. For you it sounds like a lot less expensive, I would have to replace 16 tubes.

My Primaluna EVO 400 tube power amp runs A-matched Sophia Electric EL34's. These have always been very solid performing tubes. Since the Primaluna can also run KT88's, I have been pondering buying those too.