Sounds like an impedance mismatch

What is the input impedance of both amps?

I couldn't find out what the output impedance of the piano output is.

The Roland manual states:
"OUTPUT jacks
Connect these to your external speaker system. The sound of the FP-4F can be output from connected audio
equipment or speakers"

but doesn't state anything about the levels.

If the Piano output can actually drive speakers, it will likely be way too high for an Amp input.

In the manual, under connectors it just states: "OUTPUT jacks (L/MONO, R): 1/4-inch phone type"

Can you get a 1/4" Stereo to two-mono adapter and try plugging into the Headphones output?


BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones