The Sophia Electric Princess 2A3s have burned in for 70-90 hrs now, and they seem to have stabilized. I like their SQ, excellent presence, a bit underpowered in the deep bass, but it's all there. They do not sound as slow and rounded off on the fast transients as they did after 0-40 hrs, and they definitely sound clearer with more resolution now than the NOS RCAs. I would choose these over the NOS tubes that are here.
Then I put the EML meshplates back in. They have been sitting, having burned in for >160hrs. Their SQ is really quite similar to the SQ of the Princess 2A3s -- makes me think that the main sources of the SQ now are the Bricasti M1 DAC, the i/c, and the Stratus. I really enjoy the presence, the feeling of "you are there". And now I really enjoy the deeper micro-detail, the control, the sense of solidity, and the outstanding clarity of these EMLs. The bass is outstanding, which gives the sense of presence a real visceral quality, easy to drift into emotionally and just enjoy the music.
So, at present, my order of preference is EML mesh, Sophia Princess, NOS RCA blackplates, and then stock Shuguang.
I should stop now and enjoy the music, right? Yup. Well, I ordered the new Shuguang Treasure Natural Sound 2A3C-Ts that I found on ebay yesterday, and I plan to follow up on Frihed89's suggestion and order the EML solidplates tomorrow. Madness? Obsession? I am absolutely convinced that the Stratus is a top-quality amplifier, and I want to have the best possible tubes in it. I'll be happy to share my impressions, as I hope all of the new owners will. I heard that the next Stratus was just shipped