To run a rack unit EQ you need an amp that has a send and return jack. If you don't have an effects loop then use a pedal type/stomp box EQ.
15 band is enough. 31 band is overkill.
I have used many Rack unit type of EQ's and never had any noise issues (unless you are trying to feed instrument level into it, then plugging it into the front of your amp which would make it noisy)
Harke, and Peavey make bass amps with graphic EQs instead of pots for tone adjustment, so using a graphic EQ is not really forbidden on amps. My Mesa guitar amp has one also.
MegaBass head, SWR 210, Trace 115, Ibanez RB999, 27" Imac I7, Onyx 1640I, Motu Ultralite