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
Find the amp whose sound you like, then contact the manufacturer to see which brand of tubes he recommends and which setting to bias at. Different brands in different amps perform differently. Also, the guys at the tube store (.com) have a lot of experience with this subject.
to blues man and the few last posters, I am not an audio novice. It's just that I am a tube novice. I know listening is top priority. It's just that I am not a tweaker. I don't want a lot of down time due to finicky tubes, long warm-ups etc. My listening time is limited as it is. To use an analogy from the the world of cars and bikes, I never understood all the tweaking that the early Harleys or British bikes and cars required. Seemed their owners spent more time fiddling with them than actually driving them. Have the same fear with tube power amps.
I have had great success with the Music Reference RM 9 MK II
amplifier. I have had EL34's in there for years already, and I still have no problems with noise or sonics. This amp
creates a good argument for tube reliablity.
I've been very happy with CJ tube amps for reliabilty, sound, and ease of tube replacement and rebiasing. I'm running the CJ Premier 11a as it does a fine job with my Thiel CS 1.5's. I'm not familiar with your B&W's and if they are in fact "difficult to drive" then you might want more power and that usually equates to higher cost. (not talking about low power SET amps here as they do not apply in this situation).