I have heard that a tube amplifier will be louder than a solid state amplifier of the same wattage. Is this true? Any additional info you have on this topic would be appreciated.

>> Yes, it is true that a valve amp is louder than a solid-state amp with the same RMS power rating. Of course, 100W RMS is 100W RMS whether its valve, solid-state or steam powered, but there is a difference in the way these amplifiers work with typical plucked guitar signals, and in the way these amplifiers are rated.

A solid-state amp is usually rated at it maximum power at a very low % total harmonic distortion (THD) which means it is really clean up to its maximum power. What the ratings don't say, is that it turns really dirty very abruptly just over its maximum power rating. The abruptness of this increase in distortion is quite unsuitable for percussive sounds (such as a plucked guitar string), because when you get near the maximum power, the plucked portion of the sound produces a dirty "spitting" type of distortion whith then decays into a super clean sound (quite unnatural).

On the other hand, valve power amps have a very gradual increase in THD before and after the amp reaches its rated power. Valve guitar amps are usually quoted as watts RMS at something like 5% THD. This means they produce less power a little cleaner, and more power with a little more overdrive. This is the real reason valve amps sound louder, because they can produce more power without an apparent transition beyond its rated "maximum" power.

Finally, (abruptness aside), the "quality" of the overdrive (the THD you hear) is quite different between the designs. Most guitarists prefer the smoother sound of valve overdrive to the harsher sound of solid-state overdrive, although solid-state distortion is preferred by some thrash and metal styles.