No Amp - This model has no preamp or power amp model.
Tube Instrument Preamp - This model was created to be a solution for plugging the output from an acoustic guitar’s piezo pickup or a bass. It can also deliver some tasty tones with a standard electric guitar. With the tone controls at 12 o’clock, the EQ is “flat.”
Line 6 Piezacoustic 2 - This one is designed to work with the piezo output of solidbody