EAT KT-88 tubes

I purchased eight EAT KT-88 tubes for my CJ amplifier. They sound fantastic, but two tubes went bad in 300 hours of use. Has any one else had issues with these tubes?
Hope they are still under the 6 month warranty! Normal power tubes are supposed to last for about 2,000 hours, so how come these super duper tubes failed at 300 hours? There are a lot of KT88 tubes that have excellent sound for a lot less money. BTW, I have a CJ power amp also, but it uses 6550 tubes. I wanted to roll the 6550's to KT88's and so I spoke to Ed at CJ. He told me it would not be a good idea to replace the 6550's with the KT 88's, because in all likelihood, I would be unable to bias the amp. Hope you didn't do what I was going to do because that could be the reason for the quick tube burnout.
Of course it was after 6 months. EAT/Music Hall replaced the first tube, but I haven't received a response on the second.
For the statistics: in 8 months (please don't ask me how many hours that is, though) no problem of any nature with the two I've been using. Keep my fingers crossed.
how much does a pair of these kt-88 tubes cost? where did you buy it? heard from review they can make your 2k amp sing like 20k amp.
In Germany EUR 450,- for a pair (matched, obviously).

Ignore those exact figures for a moment. I bought them for my EUR 2.2k Unison S2K, a very big leap of faith indeed. But one I have never remotely regretted from the first moment on. Can it compete with a 20k amp now? Don't know, but it sure has become another amp, definitely better in every respect (you're spot on:"sing" is indeed what it does).
I just received word from Mussc Hall that the second tube will be replace at no charge. I think the US retail is $800.00 for a matched pair. Expensive, but worth it.
Exelchuck, I am sure they sound spectacular, but certain factors have to be weighed, like the fact that it would cost me $4,800 to retube my amp with the EAT tubes!!