Typically these types of amps are attributed to a warm, full tone. When the valves are driven and pushed hard is where they come into their own, not to mention the staggering volume they can churn out. The tube saturation is what guitarists are looking for when the tubes are pushed hard, generally close to their max. The “max” of a 50-watt amp occurs at a lower volume than a 100-watt amp, so we can get great tone from a lower-wattage amp. The result of having valves is a tone that enhances low frequency harmonics, and introduces a mild distortion when driven that results in compression. How much power or wattage you need your amp to be capable of producing will vary depending on what you need your amp for. A 100 watt valve amps makes sense if you’re playing venues large enough. However using a 1 watt valve amp is a great way to get the valve sound in a practice amp. You will tend to pay more for a valve amp as guitarists thrive for that warm sound that
compresses and changes character as the player increases the volume of plays harder. It could be argued that you can’t really recreate a valve amps sound without the use of vacuum tubes! Classic amps such as the Marshall JCM’s, Fender blues junior/deluxe’s/Devilles, Orange’s, Peavey’s classic 50, Mesa Boogies Mark V and the Vox AC30. Things worth remembering when it comes to valve amps are the fantastic warm, full bodied tone they create. They can be heavy and less reliable than other amps although this is usually down to valves (tubes) that need replacing which are fairly straight forward to replace. They are less versatile than some other amps. This usually isn’t a problem as guitarists looking for a valve amp are seeking a specific sound anyway.