Zmanastronomy is correct.
Black Treasure is produced by Shuguang, Sophia are relabeled Tianjin/TJ. I'm not sure if Sophia performs any additional verification or procedures on these tubes.
In speaking to Shuguang, they have repeatedly told me there are no potential benefits in terms of measurements, sonics, reliability, or longevity of Grade A/Premium over the "standard" tubes, as both are culled from the same production lots, with no prior knowledge as to what tubes should slot where. You are simply paying for different measurement procedures and packaging.
My own evaluations via testing, listening, etc. confirms the statement regarding sonics, though it's still too early for me to comment conclusively on medium - long term reliability and longevity.
From what I seen thus far, this "grade inflation" does not justify paying more for tubes.
Black Treasure is produced by Shuguang, Sophia are relabeled Tianjin/TJ. I'm not sure if Sophia performs any additional verification or procedures on these tubes.
In speaking to Shuguang, they have repeatedly told me there are no potential benefits in terms of measurements, sonics, reliability, or longevity of Grade A/Premium over the "standard" tubes, as both are culled from the same production lots, with no prior knowledge as to what tubes should slot where. You are simply paying for different measurement procedures and packaging.
My own evaluations via testing, listening, etc. confirms the statement regarding sonics, though it's still too early for me to comment conclusively on medium - long term reliability and longevity.
From what I seen thus far, this "grade inflation" does not justify paying more for tubes.