I have a Yamaha Rx-v595a from a couple years back. I just purchased the vp-150 and the m22ti's. The receiver has a switch in the back to select 1 of two options.

Option 1: MAIN, CENTER, REAR all 8 ohms or higher
Option 2: MAIN 4 ohms or higher, CENTER 6 ohms or higher, REAR 6 ohms or higher.

Every one of my speakers are 8 ohms, except the vp150 which is of course 6 ohms. So which of the two options should I go with??