Mixing Speaker Impedance?

The switch is for the amps protection so that it doesn’t get too hot.

Wont setting the amp to 4 ohms limit speakers with 8 ohm requirements?

This setting limits the amp, since it alters the operation of the amp to run cooler, that typically results in less power output capability. The 4 ohm speaker requires the most power, with the 6 ohm being less, and the 8 ohm less than that. Also, the size room and how loud you play the system are factors. Obviously, louder volume and larger rooms require more power. In a way this may not make sense, but as I said, it is to protect the amp, by limiting its output to stay cooler. Ideally it is best use a 4 ohm rated amp with 4 ohm speakers.

Just curious as to the choice of a 9 channel amp for 5 speakers, if you don’t need the extra channels, why not get a 4 ohm rated 5 channel amp?

Sorry Zd, a vertical bi-amp means using one stereo amp per speaker, therefore L & R are totally independent. Horizontal bi-amp is a one amp for low input of both speakers, and another amp for the high input of both speakers. We will probably need to call this scenario a horizontal bi-amp since all channels are in the same chassis.

The amps rated power is 150wpc with 2 channels driven, and HT Review’s measured power on the amp is 119wpc with 5 channels driven. The OP said he was considering the purchase of this amp, so IMHO, I would take that amount, plus the additional for extra interconnects and cables needed to bi-amp, and purchase a good 4 ohm rated 5 channel amp with more power. The RX8’s will perform so much better, and the center and surrounds will benefit also, especially, if he is in a large room.