how come there is an 6-8ohm setting in my receiver?

So if I plug a pair of m80, they will potentially use 300w while the vp150 get around 200w?


specs
Number of channels: 3
• Amplifier Class: Short signal path A/B
• Output design: Triple Darlington with On semi-conductor output stages
• Differential Drive: Dual Differential input
• Types of inputs: Both Balanced (XLR) and Un-balanced (RCA)
• Type of outputs: Audiophile quality 5 way binding post
• Display type: Digital status indicators

8 ohm rating:
3 channels - 8 ohm = 200 watts per channel
2 channels - 8 ohm = 250 watts per channel
1 channels - 8 ohm = 300 watts per channel

4 ohm rating:
3 channels - 4 ohm = 300 watts per channel
2 channels - 4 ohm = 400 watts per channel
1 channels - 4 ohm = 500 watts per channel