The Tone Secret is the Tube Screamer sound you've heard on classic recordings from SRV to John Mayer, but can't recreate without a cranked Fender amp whilst using a TS pedal to push the amp into further overdrive as an EQ/Boost, without the use less than 50% of gain from the pedal.  Look at any of SRV or John Mayer's TS pedals, and the gain is almost always under 9:00, and never over 12:00 noon.  Meaning, the drive being produced by the amp alone is just an much a part of the tone as the overdrive from the pedal is.

What makes the Tone Secret superior to the TS-style pedals before it, is it takes into account these elements of the amp distortion and the pedal overdrive one package.  The Tone Secret has the preamp section of a Blackface style amp with an independent "Master" to adjust how dirty the preamp section is, in addition to an independent "Volume", "Treble", "Midrange", and "Gain" controls (called GRIT) for the Tube Screamer side of the circuit.

By having separate controls for the "Blackface" style pre-amp and the TS-style circuit volumes, you can dial the best ratio of amp-gain versus pedal gain, and control the EQ to best match with your amp of choice.