Going Tubing

I generally agree with both responses so far. Only thing to counter Jason’s comment is that while his statement is generally accurate, I would say that coloration depends on the design of the tube preamp or amp. I have heard very colored tube preamp (e.g. Cary SLP-05) and not so colored tube amps (e.g. Audio Research REF 150 SE), but in most cases, a true tube amp likely would add more coloration that most tube preamps.

Depending on the speaker’s impedance curves and sensitivity, one may prefer to match them with tube or solid state. Many opt for a tube preamp with a solid state amp because it can deliver a harmonic presentation while confidently controlling a wider variety of speakers. If the speakers are hard to drive, the requirements of a tube amplifier tends to go up exponentially, as does the price. 

A tube amp with an output impedance of 1 ohm and greater will have the most effect as the tube amp will track the speaker impedance and will not have a flat response (Ohm's Law). It will act like a tone control. So "colored" sound is the result.

Typically most folks tiptoe in by getting a tubed preamp first. They are very low maintenance and will refine the sound. Then later once they are comfortable with tubes jump into tubed power amps. They will produce a bigger change, but typically are more expensive and if buying older equipment may require biasing and retubing which can cost some money. I finally switched to tube amplifiers a few years ago (then making my systems all tube) and am very sorry I did not do it decades ago. I have probably 5,000 hours of tube amplification listening now and vertically no different than solid state other than I retubed one component.