Tube reliability in amps


I am contemplating the purchase of a tube power amp. I already have an Audible Illusions pre-amp, which has given me virtually no problems tube wise. I would like to hear from a bunch of Audiogoners on how long power amp tubes last in the real world, do I have to keep matched pairs or sets around or can I just replace one? Also I have B&W matrix 804's and I have been told tube amps are not a match for them or that I need a lot of power (read expensive tube amp). Wavering between tube and SS, HELP.

PS. I listen to orchestral music and piano. Sometimes loud like about 90 db.

Thanks
drjjpdc
I have N804s and am about to go tube as well. From this and the Audio Asylum forum, I have found that at least my N804s will be alright with 100wpc tube amps for loud hard rock, and around 50wpc for jazz and vocals at good volume levels. Two reasonably priced tube amps float my boat at this time. The Cary V12 which can do 100wpc ultra linear and 50wpc triod at the flip of some switches ($4000 retail new) The other is the VAC PA 100/100 which does 100wpc. I have seen the VAC used here for $1800-2500 and the Cary used at $2500. There are other choices. My Cary SLP 2002 pre will arive this week . Present amp is a BelCanto EVo 200.2.
I am currently running the BC21/BC22 combo from Blue Circle and am very happy with it. Since I got this setup two months ago it's been turned on constantly. The sound is much better when I leave them on all the time. I really haven't worried much about tube life since only the BC21 preamp has two tubes and the BC22 amp is solid state. However, I just received an e-mail from Blue Circle warning me against this practice. Aside from the lightning strike consequences, they feel many of the citcuits will suffer for it and it robs tube life. They suggest a 15 minute warm up period before each listening session.
Hi, I agree w/the posters who mentioned ARC power amps for having long tube life. Both of my ARC amps use 6550's; ARC gives a very conservative estimate of 1500 hrs on these power tubes but I and other owners have found much longer life. My VT100 Mk 3 uses 6H30 supertubes for drivers, rather than 6922's as the older VT100's do, and the 6H30's are rated for 10,000+ hours. BAT gear also uses the new 6H30's w/this very long tube life. But again, these are driver tubes and they tend to last longer anyway. My ARC gear need matched quads of 6550's, so keep a spare single around just in case one tube goes bad and you have a good one to test with. About B&W 804's w/tubes: there is a guy selling his Matrix 804's and his Anthem tube amp on this site right now, I would email him about his experience running the 804's with tubes. I think 100 tube watts would be fine w/these speakers, but I haven't heard them for myself.
I've had very good luck with Conrad-Johson, first MV-75A1s and now Premier l2s. The output tubes are biased individually (and easily). And, IMO, the sound is outstandingly musical. have to confess, though, that the fact CJ is about l2 miles away is very comforting.
Gads, it ain't just the amp;It's the type of tubes within the amp.My CJ Preimerer 5a's have 16 el 34's.--Rewired for all triode. The Svets last much longer,but are dull, compared to nos Siemens which get eaten at an expensive rate.