Best kt88 for VAC Avatar Super

I don't have a VAC, but if you speak with Kevin ask him if he has listened to the Shuguang Black Treasures, to my ears they are overall more musical that the GLs , base Shuguangs, JJs, SEDS - my experience with my Ayon Spirit 2

IMO, the Shuggie Black Treasures (KT88-Z) trump everything but the EAT's and the NOS (vintage) Gold Lions. They are as good as the vintage GL's (per my own A-B) and may be as good as the EAT's. They definitely exhibit what I call 'high transconductance sparkle', like the EAT's and the NOS GL's.

Their only negative (not really, but . . .) is they take the FULL 300 hrs. to break in! Probably for the black carbon polymer coating to cure? And no one knows (yet) how long they'll last? I've been running mine for 2 yrs come Feb. (about 3500 hrs.) If you buy them direct from China, you can get Premium matched Treasures for under $400 for 2 matched pair, shipped ;--)
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I always followed Kevin's recommendations for tube replacement and bought all output tubes from VAC.

Shuguang makes the following KT88 tubes:

KT88-Z (Black Treasure)
KT88-98
KT88-SC (Penta)

BTW, the 'SC' is the only KT88 tube currently made (by anybody!) that is an EXACT replica of the original M.O.V. (Marconi Osram Valve) Company later known as GEC or Genalex (the British name of the US General Electric Co. ;--) who bought MOV and made the original Gold Lion, Gold Monarch and Blue Label GEC (all the same tube, BTW) The Penta/SC is an excellent tube, but nothing like the original performancewise.

The "Gold Lion" tubes currently made by New Sensor (in the old Russian Sovtek factory) bear no resemblence to the original design -- a statement that can be made for most of the tubes New Sensor manufactures under all the vintage brand names they managed to acquire (Mullard, Tung Sol, Svetlana, et.)

As for Kevin's recommendations, with due respect, equipment manufacturers use tubes which represent a reliable supply for them (followed by reasonable cost) but are not always the 'best' tube of that type. Sometimes their OEM tubes cause problems, as with McIntosh's use of the New Sensor "Electo Harmonix" brand (which kept blowing up ;--) McIntosh finally switched to the S.E.D. Winged "C" KT88 (the original Svetlana tube, not the New Sensor brand "Svetlana" tube ;--) which is another excellent KT88 tube.

Bottom line is that if you want to do a little research, you can almost always find better tubes for your equipment than the OEM tubes supplied by the manufacturer.

As for Kevin's recommendations, with due respect, equipment manufacturers use tubes which represent a reliable supply for them (followed by reasonable cost) but are not always the 'best' tube of that type.

I would tend to agree with this statement as it relates to most manufacturers out there. However, my conversations with Kevin regarding use of output tubes in both the Avatar and Auricle Musicblocs lead me to the conclusion that VAC is the exception. Kevin supplied me with quite a bit of information on tube comparisons of output tubes, all of them leading me to believe the VAC selected and tested were the best all around choice. As for signal tubes Kevin always recommended that I try various NOS tubes on the market.

For those interested in trying the new production Gold Lion KT-88 tubes, Roger Modjeski at RAM has quite a supply. IMO he is one of the best at matching tubes to ensure quiet performance and reliability. He and Andy at Vintage Tube Services are my primary tube suppliers.