What do you mean by "tube sound?" I think tube preamps are great because small signal tubes don't "age" much, so they're sound does not change. I think, done right, tube preamps provide a greater sense of "articulation" or "naturalness" (i.e. absence of glare) to the sound . . . and I'm not talking 12ax7 tube euphony. Tube power amps, with output transformers, inevitably interact with the speaker in ways that are not entirely predictable, changing the speaker's frequency response. The combination could be synergistic, or not . . . And, it's hard to get accurate bass from a tube amp, unless you're driving a fairly high efficiency loudspeaker.
In any event, tube power amps that generate much over 75 watts per channel have lots of tubes, generate lots of heat and suck down lots of power. And, in my experience, even in a simple amp like a Dyna Stereo 70, the sound quality changes as the output tubes age. More elaborate and quality amps (Audio Research) have been known to self destruct in expensive ways when an output tube fails.
Obviously, there are, at a price, tube power amps that do all things very well, but these tend to be both high maintenance and seriously expensive in the first instance.
In any event, tube power amps that generate much over 75 watts per channel have lots of tubes, generate lots of heat and suck down lots of power. And, in my experience, even in a simple amp like a Dyna Stereo 70, the sound quality changes as the output tubes age. More elaborate and quality amps (Audio Research) have been known to self destruct in expensive ways when an output tube fails.
Obviously, there are, at a price, tube power amps that do all things very well, but these tend to be both high maintenance and seriously expensive in the first instance.