My Yamaha RX-V371 receiver can be set at 6 or 8 OHM. Is it safe to connect two Pioneer Elite SP-EBS73 speakers to it, & if it is, should I set the receiver at 6 or 8 OHM? (I live in a high rise which was wired in the 1980’s). I don’t know an OHM from a flower pot, (but I don’t need or want to...