separation of phono power supply for marantz m7 clone

[fergs1]

Im new to this caper so please excuse any simple questions. Im starting to build one of those marantz m7 clone boards and my question is this.how imperitive is it to have a separate power supply. I can uderstand the concern with stray flux but im using grain orientated iron which should eliminate this. the first valve will be shieded and damped.with this in mind can a power supply be safely includes on the main chassis as far as s/n ratio. if so what has to be done to keep noise to a minimum.it will be a typical diy affair with a wood chassis with all iron and glass standing proud on an aluminium plate.also any other advice on noise reduction regarding phono stages would be greatly appreciated. many thanks in advance fergs