I'm ready to configure my Yamaha Aventage RX-A830, and I noticed that you have to configure the speaker impedance first. My front and surround speakers are all 8 Ohms. The default setting for the receiver is 8 Ohms, but my center speaker is 6 Ohms. Should I set the speaker impedance to 6 Ohms min on the receiver settings? Doing so, would that affect my other speakers in anyway?