Cornerstone Gladio

The Cornerstone Gladio is a double preamp pedal handmade in Italy by Cornerstone, a maker whose earlier releases centered on emulating the tones of classic players such as Stevie Ray Vaughan and Robben Ford¹². Cornerstone describes it as "not just an overdrive; it's a realistic tube-compression preamp able to take the sound into saturation" while keeping a touch-sensitive response, and the design goal behind it had a name: Alexander Dumble, whose amplifiers it was created to faithfully recreate¹³.

The pedal carries two independent channels with totally different voices, each with its own footswitch, and the channels can be stacked. The original Gladio was retired in 2022 and rebuilt as the Gladio MkIII, which Delicious Audio calls the flagship double preamp that built the brand's reputation⁴. Alongside it sits the Gladio SC, a single-channel version based on the Gladio's first channel⁵.

A Dumble-style double preamp

Dumble amplifiers are rare and expensive, and the Gladio exists to put a version of that preamp saturation on a pedalboard. Cornerstone says the design mimics "the Dumble famous preamps saturation you can specifically hear in Robben Ford's songs"². Guitar.com's 2021 review put the same idea from the player's side, crediting the pedal with "huge, eloquent tones, precise note attack, effortless sustain and uncanny ability to make every amp and guitar you use with it sound bigger, clearer and better"³.

The Gladio sits in a crowded field of Dumble-style pedals. Gearnews' roundup of Dumble-style drives listed the Cornerstone Gladio as a commenter's favorite, one commenter calling it "my absolute favorite" and tying it to Robben Ford's tone⁶.

Two channels, two voices

The two channels are voiced for different players. Channel 1 delivers what Cornerstone calls a smooth and creamy sound, transparent with a round touch-sensitive response, inspired by Robben Ford's "Cannonball Shuffle"¹. Channel 2 is the "angry" side, built for a special hard clipping that sounds a bit fuzzy with high harmonics generation, inspired by Sonny Landreth's tones¹. The double-channel Gladio as a whole was inspired by artists like Robben Ford and Sonny Landreth⁵.

Guitar.com's reviewer found channel one offered "smooth soft clipping, huge sustain and dazzling, amp-like touch response" at lower gain, with focused, articulate lead tones when the gain came up, and noted "the audacious weight of the tone, and the sheer gain and headroom available on tap"⁷. Channel two's more aggressive hard clipping suited the P-90s in the reviewer's Goldtop⁷.

The controls and switches

Each channel has its own Gain, Tone and Volume controls¹. On top of those:

• COMP switch (channel 1): chooses between two different compression levels¹. Guitar.com's reviewer described it as the switch to flip "if you're seeking lower headroom and a smoother ride"⁷.
• JAZZ/ROCK switch (channel 2): a voice toggle Cornerstone says needs no introduction¹.
• Internal potentiometers: BASS for channel 1 and PRESENCE for channel 2, for extra tone shaping depending on your rig¹.
• S/D switch: chooses between Single and Double switching modes².
• I->II / II->I switch: a central toggle that sets the cascading order when both channels are active¹.

In Single mode, only one channel can be on at a time, so pressing one channel's footswitch turns the other off². In Double mode the two channels stack, which Cornerstone describes as reaching "a huge fat Dumbl-esque sound"². Guitar.com's reviewer summed up the appeal: "Switch to double mode and stack both drives to transform a vintage combo into a colossal multi-channel monster"⁷.

The Gladio SC and the MkIII

Gladio SC. The SC is a compact single-channel overdrive preamp based on the Gladio's first channel, with the exact same sound and controls, plus a new CLEAN knob⁵. That knob brings the non-compressed clean sound into the mix, with the change in compression particularly accentuated on the attack, and its effect is noticeable within roughly the first 40% of its rotation⁵. Cornerstone says the SC tries to take a step closer to the Stevie Ray Vaughan sound, which was also achieved using a Dumble amplifier⁵. Pete Thorn, demoing it with humbuckers and with single coils on his old Strats, read the intent as "a little bit more of that steel string singer stevie ray vaughan thing"⁸.

Gladio MkIII. Released as the 2026 update, the MkIII preserves the dynamic separation between the two preamps while moving the bass response, previously locked behind an internal trimpot, to an improved external front-panel knob⁴. Both channels gained dedicated Compression toggles switching between tight/controlled and open/touch-reactive feel, and Channel 2 gained a Ratio control, a clean blend that mixes the dry input signal in parallel with the overdrive, restoring transient attack and string definition without sacrificing gain⁴. Channel 1 remains the smooth, transparent, edge-of-breakup voice inspired by Robben Ford, delivering clean-to-dirty breakup based purely on pick attack⁴.

What reviewers said

Pete Thorn reviewed both pedals on his channel. Of the SC he said⁸:

He added that it feels the most amp-like overall, and in a later video said of the family: "i really like the single channel version of the gladio a lot and the double is really cool too"⁹.

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