Know your amp deeply:preamp Vs power amp distortion
Know your amp deeply :preamp Vs power amp distortion

It is very important to understand the differences between preamp and power amp distortion, which can let player to master the amplifiers and adapt to many different playing environments. By this, we could close to such immaculate tone as our idols.They created countless awesome guitar tones. These tones given us an assortment of chills, goosebumps, and weepy eyes in as little as a single note.

What is preamp distortion?
The preamp gets the rather weak and anemic little signal from guitar then boosted it to line level. 
Preamp distortion derives from overloading/distorting an amplifier's preamp section. This is also where our sound is primarily shaped and where we are given typical EQ controls like Treble, Mid and Bass. 
Many modern amps, specifically high-gain amps, have one preamp gain control as well as a master volume control. These two controls work together to create what is a nice saturated preamp distortion sound. This allows the user to achieve a well-saturated and compressed distorted sound with enhanced sustain at lower volume levels (i.e., without overdriving the power amp section). Because these amps typically also offer EQ controls within the preamp section, this higher gain sound can be shaped considerably by the user.
Preamp distortion is also characterized by increased compression which results in a more even or flat sound. Less dramatic dynamics are typically found in preamp distortion, and preamp distortion is also like that players describe variously as "fizzy", "fuzzy", "tizzy", or maybe that "wasps in a tin can" sound."
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What is power distortion?
Power amp distortion derives from overloading/distorting an amplifier's power section. The signal was amplified by preamp then passed on to the phase inverter and out to the amp's power tubes. If the signal is of too high amplitude for the power amp section, the clean 'headroom' of the amp will be maxed out, power amp distortion start to be hear.
When an amplifier is pushed to the right part of the power amp'brink' we begin to hear and feel that classic BARK. Power amp distortion typically has a more enhanced Mid range from that of preamp distortion, and while power amp distortion does add compression, it tends to be less than that of preamp distortion. The result is that power amp distortion gives us that classic punchy, warm, vocal sound. Power amp distortion is also considered much more dynamic as it responds to the human touch on the guitar and allows the player's true dynamic abilities to shine.
But the power amp distortion can cause hurt on the ear drums. In order to achieve any substantial power amp distortion, one big power amp may have to need big space. Master volume controls are typically used to manipulate this part of the signal. Commonly, we used attenuator to get enough power amp distortion at the small volume.
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What about amps with a single "VOLUME" knob?
Some vintage amps are only with one single volume knob such as 5E3, 5F1. The single volume knob will manipulate both the preamp and the power amp sections simultaneously.The signal from preamp is through attenuation then pushed by power amp more or less.Because the power of these vintage amp are lower, so the interaction of the preamp and power sections using this simple circuit can allow for some desirable tonal benefits without the amp having to get overbearingly loud.
Finding the sweet spot and knowing your amp
With these different types of distortion, each offering their own flavors. One thing to do is to just spend a ton of time with your amp. Try out different combinations of master volume and preamp gain settings. Find out what the lowest master volume setting is where you can still get that ethereal playability while reducing the risk of being told to turn down.
Another workaround here is having multiple amps and knowing which amp is appropriate for a given setting. Small amps can also still achieve that perfect level of power amp distortion in low volume.You'll need to be very much accustomed to how each of these amps work, how to find their sweet spots, and which will be right for the space.
Certainly, a great deal of the preferred tonal palate ( interaction of preamp and power amp gains) is based around the type of music being played, the type and amount of pedals being used, etc. Many players will choose an amp with a high wattage power section simply for the clean headroom it provides, and will then rely on various pedals to produce a range of distorted sounds.
Metal guitarists, while they do require volume, will often prefer the compression and tightness of a saturated preamp stage when picking a lot of notes.
Blues players often benefit from a low-to-medium wattage amp with the power section cranked to give them a bold warm breakup with lots of charisma and dynamics.
Players who tend to use their guitar's volume control will likely see more benefit from a pushed power amp rather than a pushed preamp, as they can use their volume knob to add and subtract distortion more easily.