i've heard 100hz = mud! is that true? am looking at buying a preamp and some have the bass frequency centered at 100hz and some have it at 40hz. should i really avoid the pre with bass eq set at 100hz because boosting that frequency can make the bass sound very muddy? am asking because the pre's with bass eq at 100hz have the 3 pot pre-wired lay out and the 40hz pre's have a 4 pot lay out for some reason and i need to fit it on a jazz bass control plate without having to route anything!