tutube or not tutube

I'm a little frightened (not really, just kidding). I asked a question a while back about what would be a good pre to go with my Rotel RB1090 SS Amp and my B&W Nautilus 805's (with the expectation of moving back to Nautilus 802's or close in the next year or 2). Most of the responses were in the tube area and I really appreciated the info. But as I look more into this I feel a little overwhelmed about dealing with tubes. It seems like there's so much to know and so much to be careful about. I know a lot of you are hard core hobbyists when it comes to this stuff and I'd like to be too but it's just not practical for me right now. The things that make me nervous are: how old are the tubes on the unit I might buy? How long will they last? If I have to replace them is it going to cost me a bundle and with all the tubes there are out there how am I sure I'm getting good ones? How much does varying the tubes affect the sound? I'm guessing that some of you have various sets of tubes that you change out depending on the type of music you're listening to. I read a little bit about dampeners too and that seems like a whole science in itself. All of this sounds fun if you have the time, money and patience for it. Can one go tube without being so paranoid about all the possible complications? Am I better off just going with something like the Krell krc-hr that's on here right now? Seems like quite a bargain even though it's probably over 10 years old (but so is most of my equipment). When I do this, I'll probably have about a $2k limit. And at some point may choose to replace my amp as I slowly upgrade things so I'd want to keep that in mind as well. Anyway, I'm don't mean to sound like I'm asking the same question over again. I'm not doing that. I'm just trying to figure out if I'd really be overwhelmed by going tube or if it would really be a satisfying change.