I have a set of Cerwin Vega D9 speakers (1990) that I want to hook up to my Pioneer spec system, Spec2 Amp. The amp has settings for either 4ohm or 8ohm on rear of amp. I have done research on the PC and see a-lot of forums state they are powered by 4ohms but other CV charts show them as 8ohm speakers? I am a tad confused and do not want to harm the speakers or my amp by doing any false trial and errors. Anyone have any more knowledge on this please?