The mini toggle lets you choose between low, mid, and high compression settings, the blend knob lets you dial in the unaffected guitar signal to help it sound more natural, and the volume helps to maintain unity volume when you kick it on, or let it boost your signal for solos.

i was using the keeley compressor which is do good, but the sp compressor is for me the best guitar compressor that i ever use until now, very quiet...

Please trust me and know that this IS the best sounding guitar compressor out there

The tone is really sparkly and nice, but the controls are a pain and when I played a loud G (3rd fret 1st string) it made a faint banging distortion kind of sound in the background.