Hi:
I can only give a preliminary assessment because at the same time the tubes arrived, I sold my TOTL Marantz SACD player. Until I get a replacement, I'm currently using an inexpensive Toshiba DVD player as a digital source component.
Even with the DVD player, I can tell that the Sophia Royal Princess 300Bs are special. The best way I can describe it is that they have a super-smooth sound that reminds me of 1950s vintage WE 300Bs that I heard a number of years ago. Also, female vocals, sound-staging and both frequency extremes are outstanding.
Auditory memory is problematically unreliable but having said that, the Sophia RP 300Bs + cheap DVD Player doesn't sound that much different than EML 300Bs + Marantz SACD Player. Now, I'm not saying that the Sophia RP 300Bs transformed a $60 DVD Player into a $6K SACD player but the overall sound is a lot closer than I would have thought.
This reminds me of the few times that I hung out with some top DIY amp builder's in the NY Metro area. They would have these incredibly elaborate tube systems, giant horns speakers and the digital source was always a cheap CD player.
Getting back on track, if the Sophia RP 300Bs sound this good with a cheap DVD player, it will be very interesting to hear how they sound with a better digital playback system. I'll post an update when that happens.
Gerry
P.S. I heard back from the guy who sold me the RP 300Bs. He ended up getting another 300B amp and was wondering what I thought of the tubes. I think he wished that I would sell them back to him.