that is a vauge chart but is very effective at giving rough estimates at lower power levels, but when you step up into the realm of rediculous power (5k +) there are just too many variables to give a blanket statement on how many batts are needed for XXXX amount of power
And OP, if your wanting to do this on music i would reccomend 5-6 considering youve also got a bagged truck with pumps and such... so that would add some extra stress to the charging system