6550 or KT88 ?

You might give the "reissued" Tungsol 6550's a try for about $40 a pop. I have heard nothing but good things about both their sound and their reliability.

Just this last year I bought a Music Reference RM-200 tube
amp. The amp came with two sets of KT-88, both RAM lab tested. While they sounded pretty decent, I had a feeling
I could do better. I bought a new quad of Tung Sol reissue
6550's.....OH MY GOD! I am now convinced I am DONE, the 6550's are just that good. It just seems everything is there, be it slam, liquidity, air, you name it. Maybe I just hit in the perfect match for the RM-200, but let me tell you the KT-88's are never going back in; they sounded congested and smeary when compared to the 6550's.
I could NOT be happier.
Your mileage may vary....but luckily I am getting 100mpg.
By the way, a "matched" quad of 6550's was $105!

Atomickid,
I've heard so many good things about the reissue Tungsols that your post may have just pushed me over the top.

Where is the EH KT88 fit in here? My Zeus comes with stock EH,anything better out there?
Thanks
George

My Cayin KT88 had originally Shungyang tubes. Good, but nothing special. I tried the Sovteks KT88s and they were lifeless and thin sounding. I tried the Electro Harmonix and they were a mediocre match, too much treble and not enough bass. The were very powerful though.
Then I got me the Tungsol 6550 reissues. They clearly outperform anything else, and this is what I am using. In triode mode for classical and ultralinear for Jazz and Rock music. I suppose they would be a good match for your amp as well.