I've had this post in draft for a while now, but due to general busyness it took me a while to get around to getting it posted. - but here it is.
It's easy to take things for granted in life, and the Shuguang KT-66 vacuum tubes that come stock in the Leben CS660P power amplifier are a case in point. I haven't listened to them in a long time, and not at all with my new Westminster Royal SE loudspeakers in residence, so I decided it was time to revisit them.
You know what? They're actually pretty darn good! They present a very spacious sense of recorded space, and best the Tung Sol 6L6G reissue tubes from New Sensor in this regard. They recover a lot textures from recordings, and generally sound pretty natural, but the highs can be a little screechy on violins on the Living Stereo Clair de Lune at times, for example. Not terrible or anything, but it's there. So it's a bit of a trade-off for the wonderful sense of space and musical color and textures they're capable of. But considering that you can get a matched quad for less than $100 USD you really can't go wrong.
Comparing the Shuguang KT-66 to the Gold Lion KT-66 New Sensor reissues on Clair de Lune results in about what I would have expected, with the Gold Lion being less 'lit up' than the Shuguang, but being smoother and more luxuriously smooth from top to bottom. So like most things in life it's a trade off, with the Shuguang providing more sense of recorded space and texture than Gold Lion, but getting a little edgy on violins at times. The Gold Lion is smoother and more polite on violins, and can get a little piquant in the places that the Shuguang gets edgy, but overall it is a nice musical presentation. I confess that I do miss the extra senses of recorded space and textures that the Shuguang brings to the performance though. Which one you'll prefer will probably depend on your system balance more than anything. If your system is laid back sounding give the Shuguang a try, and if it is neutral to forward sounding give the Gold Lion a try. The Genalex Gold Lion reissues are quite a bit more expensive at around $160 USD for a matched quad.
Stop the presses! As a reality check I thought I'd put back in the Russian NOS 6n3cE vacuum tubes that I've had such good results with in my Leben CS600 integrated amplifier. Wowza! These are ugly looking little tubes, but like the ashes to royalty story of Cinderella, they positively wipe the floor with either the Shuguang or Genalex Gold Lion (and these are both great tubes!), having the best qualities of both with the downside of neither.
No etch or edge in the high frequencies, lots of detail, smooth and lush sounding, lots of gorgeous tone color, and they are motion masters that make the tempos and melodies come alive. The 6n3cE may be the best 6L6 variant tube ever made - period. To top it off they only cost $50 USD for a matched quad, and they last a very long time, and just seem to sound better with time. The quad in my Leben CS600 integrated have been going strong now for 3 years of almost daily listening. The Russian NOS 6n3cE - the Cinderella 6n3cE - magnificent!
