About Solid State Combo Amps:
Most inexpensive guitar amplifiers currently produced are based on semiconductor (solid-state) circuits, and some designs incorporate tubes in the preamp stage for their subjectively warmer overdrive sound. While this is a desirable attribute in many cases, the tube's characteristic will "color" all the sounds at any volume, unlike solid-state.
High-end solid-state amplifiers are less common, since many professional guitarists tend to favor all-tube amps. Some jazz guitarists, however, tend to favor the "cleaner" sound of solid-state amplifiers, preferring not to color the sound of their guitar with the tube distortion and compression so popular with rock, blues, and metal musicians.