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

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.

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...

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...

Thanks guys- great comments. Re: the KR 845's, KR said ~ 3,000 hours. I am CERTAINLY not going to pay the $1,700 CDN that our local Canadian distributor wants for the quad set I would need to have them last only a bit over 1 year...

However, Ecclectique, your comment is interesting- 20-30,000 hours??!! I can't believe that! Wow- if that IS the case, hey, sign me up!! Which NOS tubes are the ones with this incredibly ling life?? (and yes, I have also had the KR 300BXLS in a pair of 300B monoblocks- they are great tubes).

Also- where do you FIND these super long lasting and superior NOS 845 tubes for NOT a small fortune? (I would need 4 minimum).