What do you see as the downside of tubes?

What a great thread! I have been fascinated by tube amps for years and have never had the money or gumption to go that way,though the systems that I have heard have been magical.I am leaning more and more toward taking the plunge and going with a tube rig.I have a set of the original Snell "E 1s" and they should be a good fit for a tube amp or integrated.My main system has Acoustat 2s and unless I could aquire some serious big mono blocks would be a problem to drive.(If this is faulty thinking please say so)
The Dynaco ST70 and the upgrades/restorations available seem like a good starter path.Also I was thinking a tube preamp for the Acoustats might bring a touch of the tube sweetness I long for.
The Dynaco refurb route has a certain symmetry for me because I am driving the Acoustats with a Hafler 220,so I would have David Hafler's early and latest designs to compare a contrast.Also, it seems to me that since there are so many of them in use still that they must be doing something right.
The idea of tweaking and tube rolling sounds fun and interesting to me as well.Nothing is more fun than tweaking and discovering new magic in your system;after all,this is a hobby.
As for tubes going away in production;it seems that the Chinese and Russians are making them (military grade)in great number.(planning for Nuclear winter?)
Now if this recession/depression would just turn around,I could start shopping.:-)

I lost patience in trying to read all of the above - here are some random thoughts:

Viridian makes the most important comment in my mind - you have to spend a lot of money on a tube amp to get a good one, i.e., one having power supplies and output transformers of sufficient quality to enable it to properly drive most audiophile speakers. It's hard and risky to define "a lot", but let's say well north of $10k retail - many (if not most) tube amps are overrated and not understood by their purchasers.

Your Living Voice speakers, however, are excellent and present a benign impedence load, allowing you a lot more flexibility with respect to amp choice. I have no personal experience with the Mastersound amps. I do not want to steer you away from single-ended amps on Living Voice speakers, but a hassle-free tube amp that is really well built and sounds truly great is the VAC Renaissance 30/30 push-pull amp. It biases the output tubes automatically and has a tube shut-down feature that kills the power to any output tube that is about to blow (these features take all of the hassle out of owning a tube amp). All point-to-point wired (no boards on those babies). It runs four 300-B's and puts out 32 watts/channel - it would sound like a 600 watt/channel Krell on a highly efficient speaker like the Living Voice.

Despite the high initial downstroke, good 300-B's (Sophia Electric, Full Music, E.A.T.) will last a very long time (10,000+ hours / 5+ years).

While some tube gear is truly problematic to own, a high-quality tube amp running standard-fare pentode or triode output tubes is arguably more "reliable" in the long run than certain high-end solid-state designs - when a tube amp is retubed, it's basically a brand-new amp, while some high-end solid-state designs have been known to become irreparable because they use rarefied output transistors that go out of production. Also, you replace output tubes, while a $50/hour tech repairs the solid-state amp you had to pack up and send away to him.

A high-powered tube amp that uses a lot of output tubes can be a pain in the ass to own because of the higher likelihood of tubes losing bias and fact that easy biasing is not always a design priority (Brunhilde and Wotan owners with burnt fingers know what I'm talking about). However, if you are running a single-ended amp with one or two output tubes, or a high-quality amp that auto-biases like a VAC Renaissance or Audio Valve, there is little or no more demanded of the owner than with a typical solid-state design.

You don't have "to spend more than $10K to get a good tube amp" That's simply a fairy tale.

Raquel, just a FWIW, we probably have as many tubes in our amps as anybody, but they are autobias and hold together quite well, even if a tube fails. Having a lot of tubes does not have to be a pain in the neck if the amp is designed properly.

Rolled off highs, bloated bass? :-)