I own Shuguang Black Treasure 12au7. Two for my pre-amp and two for my DAC. I've been seduced from HifiCave on YouTube to use these tubes. Upon purchase I only bought two for my preamp.
I was floored by the sound because I heard clarity like I've never experienced before. Everything improved with the sound. The Cryotone tubes made my Black Treasures sound veiled.
My hifi improved so much, I ordered another pair for my DAC immediately.
At this point, I'm awaiting the arrival of my second set. I understand there is a process that takes place. That includes slowly freezing and warming up process. From what I hear, there's a process used for the first burning-in the tubes before they're sent to us.
These may be the perfect tubes.
I may be able to detect any weaknesses in my rig with these tubes.
I have just got a pair of 12AU7's and they are fantastic! I have tried quite a few other tubes on my VTL 6.5 pre amplifier from NOS Mullard and Telefunkent to recent JJ to Apos Ray Select but they do not get close to these Cryotone tubes. They are dead silent, dynamic and sound true to live music. I am amazed.
I still have 2 more au-7 tubes to buy, plus 4 kt88 for the power section. Because of the price and other responsibilities I have to take my time with purchasing but the improvements are amazing. The noise floor and distortion are noticeably reduced.The Musical Gods at Wathen have blessed me with amazing sound.
The tube is everything I thought it was going to be. Love it