4 ohm 8 ohm

Eldartford is correct; driving the speakers from any tap will damage neither the amp nor the speakers. The voltage delivered to the speakers (and the sound-output level) will increase with each step up the impedance taps, but the amp still won't deliver more than the same amount of power.

So you'll get more volume up to a point, which seems to be what you want, but listen carefully--the system will sound different from each tap.
.

Try it. No damage. For a given signal input you will get more volts out to the speaker from the 8 ohm tap up until the point where the amp runs out of current capability. The amp will be capable of fewer watts with this impedance mismatch, but it might play louder.

Use the 4 ohm tap. You run the risk of damaging your speakers otherwise. You can run 8 ohm speakers on the 4 ohm tap without any danger. They just won't play as loud.

Gene

I don't think that is a good idea.

Use the 4 ohm tap.