4 8 or 16 ohms.

Hi group I just purchased the Audio Research REF 750s mono amps. On the back for the speaker terminals are 3 sets of binding posts. 4 8 and 16 ohms. I will be using B&W Matrix 800 speakers. I believe they are 8 ohms but not 💯 sure. I looked in the manual but can’t find anything about ohms. Someone said to me it does not matter what ohms I connect my speakers to. He said just use the ones (ohms) that sound best. Does that seem right to do ? I don’t want to damage my speakers or amps.  BTW if it matters I will be using an Audio Research REF 6SE pre amp.