Are the better $$$ 845 tubes worth it sonically??


I have the ASL 1009 monoblocks (a pair of 845's per amp), and have the stock Chinese 845 tubes. Has anyone compared their 845-based amps with ANY other type of 845 tubes?

I am most interested in hearing about the KR 845's, as they are current production, and available from Czech at $430/matched pair . The older GE-type NOS 845's seem way to expensive.

I guess the main question though is WHAT differences sonically did you notice upon using a 'better' 845 tube, and was it worth it??
sutts
Hi Sutts- I haven't tried the KR845's, but the US NOS 845s were a huge improvement over the stock Sino tube. Yes, they are expensive. However, considering their longevity and the level of sonic improvement, I believe they are a worthwhile investment. Enjoy.
Jcb- longetivity??!! I had heard that this is where the 845's are NOT as good as some other tubes- i.e. KR themselves just this afternoon quoted me ~ 3,000 hours max for the 845 tube... That is a big concern as the system is used for HT & 2-ch, and I often have the amps on like 6-7 hours per day.
Remember the KR 845 tubes use an oxide-coated filament, not thoriated tungsten, which is what vintage 845s and chinese ones use. (Bright emitter vs. dull emitter)...

personally, yes - I think the vintage ones are worth the $. Let us know your impression of the KR ones if you get a chance,
-Ed