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
Ecclectique- thanks for the response- the biggest influence I have found so far is the input/phase split tube upgrade- went with a quad matched pair of Mullard 12au7's- fantastic! OK, I will stick with the stock 845's- my guru buddy (Israel Blume at Coincident) concurs, saying that the 845 upgrade will not prove all that substantial of a change, and is cost prohibitive...
Hey Sutts.Which vintage mullard? I found all the mullards great..but my favorite mullard is the box plate 8139.Retains that mullard tone in the mids with better resolution in the bass.If you are into tube rolling...you have to try a 60's Mazda chrome plate 12au7.They can be a little hard to find but there are lots out there with a little searching and usually quite reasonable to boot.They are easily identified by their silver plates,a lot of them are labelled GE made in France.In the 1009...they have all the body of the mullards with better top to bottom balance.I found the mullards a little rolled on the top when compared to the telefunkens,siemens or mazdas.The chrome plates have that beautiful soul of the mullards with the top end air and resolution of the teles.Really opens up the window on the stage! A great compliment for the 845. Cheers David.
Hi Sutts, how is everything?

If Jcbtubes recommends something, TAKE IT TO THE BANK!!!
Trelja- what's up guy? Jcb didn't get back to the thread when I asked about NOS 845 tube longevity- I may contact him about this...

Ecclectique (I like that moniker a lot btw!)- I am happy with the Mullards I have, but am unsure of exact vintage and don't want to go too crazy searching out exotic 12au7's, as I need 4 of them at a shot and these amps are on with HT & 2-ch sometimes 8-10 hours per day, and at that rate will be burning through NOS tubes faster than I would like...
12au7's will last thousands of hours, and they are cheap - don't worry about it. get the best you can find and enjoy them. life is too short to worry about it otherwise. Vintage 845s can last as long or longer than chinese, I think. I have probably 1000+ hours on a pair of Cetrons right now and they are as strong as day 1. Vintage 845s were guaranteed for military use (read: extreme, at times) at usually 1000 hours. Often times of course they ran far longer than that. several thousand hours would not be unheard of. I have some 1006-845 amps, I think they run @ 900v or so around 85ma - not overly hard on the tubes. if the 1009s' run them similarly, I'd expect quite a long number of hours from a pair of vintage ones.

The difference with vintage 845s, while perhaps subtle (to some), is definitely there. Value/worth depends on every individual's situation. To me, they are worth it. With some work, they can be found for relatively reasonable money. (read: about 1/2 or less than what tubeworld.com wants for them).

thanks
-Ed