id be tempted with a buffer rather than a pre amp .. most of the issues with piezos sounding thin are due to impedence miss matches.
I have one of those from Gitty but have not used it. I plan on doing what someone posted in here about mounting it in a small box instead of building it into one guitar, so then I can plug any guitar into it. An EQ box between guitar and amp.
Along those same line, does anyone have experience using a DI box between a CBG and amp/board?
a DI box will change the impedence and condition your signal for a desk but there is little in the way of EQ so its in the hands of your sound man, ive always found that a small amp mic'd up (even just a few watts) give you a much bigger tone and more control