Al is correct. DO NOT use both sets of speaker outputs unless you are certain the speaker you are using does not dip below 8 ohms impedance at any point in it’s frequency response or you will most likely damage the amp. If you want to biwire, run both sets from the same speaker outputs.
“Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”
Hunter S Thompson