Mad professors Evolution Orange Underdrive is a relaly intriguing pedal. Instead of pushing your tone like a traditional overdrive, the EOU works by lowering the midrange as that is where the overdrive mostly is. You can dampen the amplifier input with the EOU’s Volume control and then set the Bass and Treble to tailor your clean tone. EOU can also be used to boost mids by settings the Midrange and Volume up
Here's what Mad Professor have to say about this pedal
Evolution Orange Underdrive (EOU) offers a new way to approach your tone. Instead of overdriving your clean tone, now you can get cleaner tones from your favourite overdriven tone.
That is what we call underdriving.
Evolution Orange Underdrive works really well with vintage single channel amps that sound great when you push them to overdrive.