Good post above by Nsgarch, to which I would only add it is usually much less expensive to retube a tubed preamp than a power amp, and the tubed preamp generally gives off much less heat. Also, the bass control issue extends to tubed preamps as well as power amps, with a few exceptions, although even the really good ones do not equal the bass control and definition of the best SS preamps. However, it is very hard to equal the dimensionality and harmonics of a tube amp or preamp when using SS.
