Marceline has been shown to own amps.
Marceline's Primary Amplifier debuts in "It Came from the Nightosphere." It can be seen in the background as Marceline plays the "Fry Song." It makes another appearance in "Go With Me" when Marceline is about to practice her Ax bass, but she is interrupted by Finn. Its most recent appearance was in "Heat Signature." The control panel features four dials: volume (far right) and the remaining three most likely tone controls (bass, midrange, and treble). It also has a power switch and a headphone jack. Marceline's name is inscribed in purple, cursive letters beneath the control panel; this is likely to be an homage to one of the most popular factual brands of amplifiers, Marshall, which uses as its logo the cursively signed surname of its founder Jim Marshall, and which bears phonetic similarity to Marceline's name.
Marceline also owns an auxiliary amplifier, used with her auxiliary bass. The auxiliary amp appears in "Evicted!," before her battle with Finn. Like the primary amp, Marceline's name is also inscribed on the surface of this amp.
In Righteous Quest 2, Marceline will send Ninjas and Amps to be an obstacle so that Finn and Jake would try and get back Jake's Viola. The Amps will shoot soundwaves that will cause damage if being hit with, the good thing about that is that they only point in the left direction. Later, in Marceline's Chamber, she often uses amps that disappear after they fire during the first stage of the fight.