how would an entry-level tube system compare?

Thanks for all the feedback everyone.

As Bignerd100 and Tvad correctly guessed, I really do want to experiment with tubes for a variety of reasons. A lot of the music I listen to is very well produced and has many nuances that I'm expecting tubes to accentuate. Plus I'm in the mood to try something new. Plus the concept of tube-rolling appeals to the DIY-er in me. Plus 25% of the other music I listen to is tube-friendly. Plus they look cool.

Bartokfan - I wasn't aware of the wear-and-tear factor on tubes of loud, driving music. It makes sense. But I think it's a reality I'm willing to live with.

So given the <50W factor, based on all your comments it seems that high-sensitivity speakers are key. So my natural follow-up question is: how highly sensitive do I have to go? (I should qualify that my statement of wanting to shake the house was somewhat hyperbolic.) Do I need to be thinking about 100db+ sensitivity, or will 89-91db (which seems to be the sweet spot in terms of offering the largest number of options) suffice?

Thanks all...

PS Barktofan - I'd be curious to know where you see Cayin A88's for $1000 used. I'm seeing more in the $1500 used range on Audiogon. Please let me know...

Just a couple of suggestions:
1)Listen to a mid-priced horn system to see if it is to your liking. This will give you the largest performance/dollar return.
Teh problem with horns is that you like them or you don't and they have to be very large to produce deep bass.
2)No mater the design of the speaker stay above 93-94db efficency. Even 84db efficent speakers can sound wonderful with low powered tube amps for everyday listening but it is when brief peaks demand power that it will run out of juice and sound terrible.
3)Single driver, high efficency speakers can sound wonderful too. But for huge swings in dynamics they are likely to fall short.

If it is in your price range Tyler has come out with some beautiful horn-loaded speakers. Also check out Pi spekaers. You can buy them preassembled or as a kit. The guy who owns the company is very nice and accomodating. Old JBL or Klipsch should be high on your list too. Possibly Bag End PA speakers even.

Good luck!

Defiant, you do not need high sensitivity speakers with tube amps, at least not high quality tube amps. The 2 that come to my mind are Jadis and Cayin. i have the smallest of the Jadis' a 40 watt!!! , the Orch Reference, has 4 KT 90's driving the hefty and very low sensitivity Seas' rated at 87/86 db,. I guess you could say power hungry but the Jadis drives them with ease. Other labs in that size tube amp will not match, the Jadis is famous for its well constructed and its stamina/power. The Cayin A88 will drive the Tyler's Big is mentioning. But I would not go above his MTM(Monitors, with 7inch/tweet/7 inch) or 3 way(8 inch, 7inch, tweet) model. Sure its a hefty demanding dribver, but the Cayin, from what I read is up to the task. There are a few tubes amps that are best/only for high sensitivity speakers, the famous 300B tube is one. But don't worry about that right now, thats for another topic.
I should say with hesitation that the Cayin A88 has the KT88 tube and my Jadis has the KT90 tube. In tubes numbers mean alot. I'm thinking the 90 delivers more bass, sweeter highs. The 88 is a shorter tube and is better in mids. If that is so, then the A88 will not work with Tyler.
I bought a quad of 88's for my Jadis, and they sounded like c**p. But they were not Jadis 88's , but a cheap brand. So I do not know what the deal is. What I really need to do is get my hands on the A88, ASAP.
September, maybe August.
Used sometimes for 1K, keep eye open they go fast. I can get one from Hong Kong as well.
Paul
Paul