The Sophia Royal Princess seems over priced to me.
If I'm not mistaken it is a re-labeled TJ Fullmusic 300B SE which goes for $700 on eBay.
Even with shipping in doesn't reach $1,200 so what gives?
Meanwhile Psvane 300B-T which is an improvement over the former Shuguang Treasure Z (as warm and liquid but more sparkle on top, more transparency and better bass control) goes for $510 and KR goes for $525.
Is the Royal Princess that much better? I have some doubts but than we are in the hobby of diminishing returns.
Of course the circuit of the amp and the interaction with the speakers may give an edge to one set of tubes over the other so this discussion becomes somewhat subjective.
Case in mind is a friend of mine heard the TJ Mesh Plate in some SET galore in Hong Kong and thought it was super sweet as output tube but as a driver tube in my amp we both thought that although it was more transparent and airy than the Shuguang Treasure, it was bright, a bit grainy and gave a flatter presentation than the Shuguang Treasure.
The Treasures are not the last word in transparency or air but are very liquid, dense and present very good image depth which is quite seductive.
My latest experience is that the Psvane 300B-T are a noticeable improvement.