6CA7-Z / KT88-Z or WE 6CA7Plus / WE KT88Plus – which one?

Answer to an inquiry from Germany – related to Unison Simply Italy:

6CA7-Z and KT88-Z were released over 10 years ago to the market as the very first high end upgrade tubes. But over years, the factory’s lack of quality screening has flooded market with mixed quality. We (Grant Fidelity) no longer carry them as the ‘selection’ cost is simply too high and performance varies too much. 

6CA7- ‘they are exceptional tubes’

from customer Lyle C. by email:

“Greetings,
I bought a quad of the Shuguang Black Treasure 6CA7’s from you recently and love them. They are exceptional tubes, absolutely killing the EH 6CA7 and Tung Sol reissue EL34’s I’ve tried.”

6CA7-Z Treasure tubes – recommended

Posted by forum member:

I would recommend the Shuguang Treasure 6CA7-Zs, as tested and screened by Grant Fidelity, as a substitute for the EL34s. The additional cost is well worth the better Grade A. I noticed that the heat from the Treasure 6CA7-Zs is substantially and significantly less than the heat that emanated from either the Siemens or the JJ KT77s or the EH EL34s. That thermal difference could well mean a longer life-span for the Treasures.

It’s emotional..

by email from customer Kevin K.

‘Hi Rachel,

Thank You! The tubes arrived today and I can best describe them as “emotional.”  I have had the CD 327a powered on for two days now and listened to Rickee Lee Jones and The Durutti Column through the Treasure Series this afternoon and they sound very good already. Perhaps the selection of tunes has to do with the “emotional” tag; I dunno…’

‘they sound better than the best Mullards I have’

– from customer Richard J.

“Dear Rachel, First I would like to say Thank You for sending the Shuguang Anniversary EL 34 Black bottle tubes. Amazingly they sounded better than the best Mullards I currently have on hand right out of the box. I have never had a tube sound so good with no break in time, and I have been using tubes since 1963. Thease are trurly an amazing accomplishment. ”