Volume
Everything to control the volume level of your pedalboard.
The low-impedance Volume Control Box is intended for the effects loop of the amp. There it allows the preamp of the amp to be cranked and at the same time to reduce the volume to a tolerable level.
The high-impedance Volume Switch can reduce the volume of the guitar - similar to the volume control on the guitar, but without changing its sound. Due to the reduced level, it reduces the degree of distortion and the compression of the preamp of the tube amp.
You can find a more detailed explanation of the differences at the bottom of this page.
High-impedance vs. low-impedance volume pedals
A tube amp consists of two amplification stages, the pre-amp, which shapes the sound with an equalizer and gain control, and passes a low-impedance signal on to the second stage, the power-amp, which drives the speaker.
Between the pre-amp and the power-amp, many amps have an access point, the effects loop, into which additional effects can be inserted that further process the sound formed by the pre-amp - e.g. delays and reverbs.
The output signal of a guitar with a passive pickup is high-impedance and very weak and therefore requires a high-impedance volume pedal specified for this purpose in order to prevent high-frequency losses.
The output signal from the vast majority of effect pedals and the effects loop of the amp is low-impedance, so if you want to reduce its volume, a low-impedance volume pedal is the best choice, as it allows a linear control path, among other things.
If you reduce the volume before the pre-amp, the sound, overdrive and compression changes (this roughly corresponds to turning down the gain knob of the preamp), if you reduce the volume between the pre-amp and power-amp, the volume of the amp is reduced (similar to the master volume control of the amp).
Distortion and fuzz can also be regarded as pre-amps, if they are in the signal chain it has several preamp stages (gain stages).
