tubes for leben cs600

when i bought my leben i get it with GoldLion kt77 genalex russia .now it in the end i search on ebay about this kt77 and its much more expensive then the Tung-Sol 6l6gc, i like to know why and if the price is the diffrent or the quality is better in the kt77 goldlion or maybe is better to buy Tung-Sol 6l6gc ??
i order 2 6CS7 - Sylvania from Jim (because he have only 2 in his stock), and 2 others 6cs7 from ebay Sylvania USA Black Plates NOS Double Triode Leben Re-Branded for Westinghouse Canada .
is it all the 4 tubes 6cs7 will work togther very good or because they are 2 tubes from Jim and 2 from ebay but they same tubes sylvania 6cs7 and just diffrent companies and the 2 tubes from ebay NOS Double Triode Leben Re-Branded for Westinghouse Canada is this different (i really dont know what that means double triode ) will effect the sound or will make the sound not shine or it will be very good ??
please tell me
im really not understand alot in tubes only few things basic things
thanks alot and sorry about my english

Bolero - I can't say for certain why one tube costs more than another except for the usual: supply and demand. IMO it has more to do with performance in the targeted amp. In this hobby subjectivity is king. The beauty of this amp is the flexibility an owner has in trying out 'many' different tubes! Each tube characterized by its own signature sound.

Check with Leben (muson@leto.eonet.ne.jp) about mixing different brand tubes within the CS-600. Since this amp is auto-biasing you may be alright. I always put in a matched quad just to be safe and have never 'mixed' different brand tubes in the CS-600 WRT the power tubes. Most probably would not.

See the linked sheet for possible power tube combinations sent to me from Yoshi Hontani (Managing Director):
CS-600 TUBE COMPATIBILITY LIST

Sounds likes you've only had the KT77's in the CS-600? What other's - if any - have you tried and/or compared them to in the amp?

If you haven't started your "rolling" (tubes) adventure then buckle up and get ready for the ride of your life.

enjoy the music...

EL34 and 6l6GCs have pretty different sound signatures so it will be different as EL34 have a lot more warmer lusher sound (Generalising) and 6L6GCs much more bolder and wider across the range (Again Generalising)
for the price the Russian 6l6GC reflector equivalents (6n3c e) are great..they are not expensive and definitely better than the SED6l6GC i used in the past.

But for me..as has been mentioned by Notec, the KT120s are in a different league altogether . the 6cS7s, at least to me do have an impact but its minuscule in comparison and in my opinion, need be on ones agenda only after changing the power tubes.

I only have kt-77 since i bought my leben used.
But i dont wanna play alot with the tubes just wanna know from yours experince what will be the best combinition ?
All i know kt 120 need open the cover of the leben and in my place is inpossible i have kids and its on my furniture table in the center of my living room.
My dealer can send me from japen the original set of the leben and its coast after taxs and shipping to israel 400$ much more expensive then Jim suggestion but i still not understand if the original tubes what leben company put inside the leben will be the mark of leben sound this is the reason that we buy leben or to play with others tubes that maybe will give better sound and much more quality who can say what better the tubes that leben put (maybe they put cheap tubes or standard tubes to save money or they put better tubes from what we put i means the companys and the quality)what will be the better chioce or what the diffrenet in the sound
leben company tubes or Jim suggestion and what better kt77 or the Tungsol 6l6gc-str ???
Please help me understand

the "original" in my case was Sovtek 6L6GC and any new tube was better !
With the KT-77 i would think your sound will be good and that unless you hear different ones , not be able to evaluate any different tubes.

Yes with the KT120 you cannot put the cover back on so that is out . if you are trying 6l6GC the 6n3ce is a far cheaper And better option. I am pretty confident this will be better than the GEnalex KT77 as well ..a s in my case i prefer the larger freq extension of the 6l6GC to the lushness of the KT77 (or EL 34) but individual tastes can vary hence cannot say how it will work for you