Suggestion request: I have a Lexus GX470 Mark Levinson system. From what I understand, the speakers are a low hanging fruit weak spot, and are readily upgradable. What would you replace them with for max driver EQ experience? Let's assume a sizable budget. I haven't found anything technical on load balancing - could one go with 8ohm sub & woofer while going 4ohm for mid/tweets without risking the amplifier. The idea is adaptable speakers without rewiring.