????
Unless I misunderstand your question???
You don't need one. The tryos is an excellent auto accompaniment module as well.

What is your main instrument as one man band, in other words what instrument are you playing?
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Keyboards/Sound Units: Kurzweil 2600S, Roland VR-760, Acces Virus C, Roland G-800, Akai AX60, Minimoog, Machine Drum, Roland R8-M, mediastation x-76