i need a little help choosing which kenwood excelon kdc to buy? Im going to use just aftermarket door 6.5 infinity reference 6502ix coax speakers 2 front and 2 back , I dont want a amp. just head unit and speakers. so kenwood has kdc models- x998, x898, x700,x500 . the 998 has 93db and the x898 and x700 had 90dbs? do db, s matter?