The correct amplification of modern guitars is always a subject, but even more so, if you use a Polybass.
Guitars amps are not made for such low bass. But most bass amplifiers can handle the treble of an acoustic guitar even better than a guitar amp anyway. Try Schertler B10 for example.
Often, the best is to connect to the PA directly. Independently of the Polybass, Paradis-Guitars has recommended this way to most of their clients. sure, if you want to play standard rock or imitate some traditional electric guitar, you best use the instrument and equipment of the original.
but in all other cases, its much more practical and probably more comfortable for your public if you use the house system like any other instrument on stage!
here the reasons:
Distortion is altered in rather unpleasant way if the low frequency of the Polybass is strongly present in the mix you send to the distortion. So if you use a magnetic pickup as well, consider to split the guitar into two or even three way of amplification: the magnetic pickup can go to a typical electric guitar system with distortion effects while the piezo goes to the PA or an acoustic amp and some even want the Polybass effect on a separate channel to keep it dry.