Tube change.

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. 
 

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

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

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