Keller's main workhorse is a Martin HD-28(L) from the early 2000s. It has "the low end of a beast" and is plugged direct into the PA. He also has another HD-28 that is used for more experimental purposes–such as adding a synth pickup or even cutting it in half. The thin-bodied guitar on the right caught Keller's eye online for $180 on Amazon when it was described as an "acoustic SG."
He also uses an electric guitar made by Tommy Rodriguez out of Richmond, Virignia and a Fender Road Worn bass. He strings it with flatwound strings and turns the tone control all the way down to take all the treble out of his sound.
The heart of Keller's pedalboard rig is a Boss RC-300, which everything feeds into. His favorite effect–due to Jerry Garcia's influence–is the MuTron III. His other main effects include a Line 6 DL4, Ibanez Tube Screamer, Boss Digital Reverb, Boss RT-20 Rotary Ensemble, and a TC Electronic Hall of Fame Reverb. Keller is able to blend the effects with his dry signal via an Ernie Ball VP Jr. Volume Pedal. He runs everything direct with no amps.
In addition, the Korg Kaossilator gives Keller access to some synth-style sounds–which are also run through the RC-300. The Roland HandSonic HPD-15 gives Keller all the drum sounds he needs to create his loops, and he also uses a Roland GR-55 for all of his synth sounds (with the Rodriguez electric).