Tube change.

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. 

@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.

@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.

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.