I have seen that some of you Zon owners (Custom, Special, Legacy models) have Bartolini Preamps instead of the standard Polyfusion ZP-2. Why did you go with the bart? And which Bart preamp is it? Or, same question, different approach: What didn't you like about the Polyfusion preamp? (All Zonners: Are you happy with your Polyfusion pre?) Thanks for your input!