Catalinbread built the Dirty Little Secret around one specific question: what if your amp already sounded like a cranked Marshall stack? Not a Marshall impression, not a gain pedal that vaguely hints at British rock — the actual circuit topology of a Super Lead and Super Bass, running on your pedalboard.

There are two modes inside, selectable via an internal switch. Super Lead gives you the mid-forward kerrang of a classic Plexi, with gain that runs from touch-sensitive clean all the way to early JCM800 territory. Super Bass is the one for players who want that in-between thing — not quite clean, not quite crunching — where real non-master-volume amps lived. Both modes use the exact tone stack values from the original Marshall circuits. Not approximations. The actual values.

The design intent is that this lives on your board permanently. Roll your guitar volume back and you're clean. Dig in and the character comes through. Stack drives or fuzzes in front of it the way you would in front of a real amp. The DLS MKIII is the third revision of this circuit, and the most refined.

Volume, Preamp, Bass, Mid, Treble. True bypass. 9–18V DC — running it at 18V opens up the headroom significantly.