A tube amplifier is a linear device; meaning, it is intended to exactly reproduce the signal fed into it, only louder. Tubes and transistors both do that job, but they do it differently. A tube amplifier is usually considered to sound more 'graceful' and more musical on acoustic music and voices. The best amplifiers will combine both characteristics. A tube amplifier is susceptible to loading, for example, and has its output power optimized when loaded by its rated matching impedance. This means that a lower-impedance speaker may not necessarily sound louder, due to the mismatch between the peak-voltage:current ratio available from the amplifier.
A tube amplifier is oftentimes the most costly, but, at the same time it's going to give you the better sound. A solid state amp will probably meet your requirements if you're searching for a high powered amp that won't cost you as much.
Tube amplifiers are heavier and require more careful handling. While the sound generated by the tube is truer, it is often not as vibrant as the sound of the lighter solid state amp. Tube amplifiers are more expensive, and can cost up to $500 to $1000, depending on the brand, sound quality, and features. Beginners usually cannot afford to spend such a huge amount on buying a tube guitar amplifier. Tube amplifiers are sought after for their textbook warm sound. Although both are very similar in sound some people think vacuum tube amps are better due to better output at lower power.
Tube amplifiers are a delicacy appreciated by the purist with a flair for midrange reality. The Jolida amplifier supplied a delectably palpable midband that is sure to put goosebumps up the spine of any vocals enthusiast. Tube amplifiers are favored by guitar artists and musicians all around the globe for the exceptionally enhanced sound quality that they deliver. Amplifiers came into existence for allowing distortion free transmission of input signals, whether audio or any other. Tube amplifiers are also far more responsive to the dynamics of a guitarist's playing (how hard she hits the strings). Tube amplifiers, when played hard, produce some desirable grit that solid state amps do not.
Tube amplifiers are said to sound more musical. The reason is that tube amplifiers produce even ordered harmonics. Tube amplifiers are generally not very efficient and tend to generate a lot of heat. One of the biggest differences between a tube amplifier and a transistor amplifier is that an audio output transformer is almost always required in a tube amplifier (this is because the output impedance of a tube circuit is far too high to properly interface directly to a low impedance loudspeaker).