Hey, I recently purchased a QSC mx1500a power amp for my pa system, but my first trial with it, its not delivering nearly enough volume for what it should. I tried it on mono, bridge, and stereo, but it's just barely over speaking level. I've attached the banana clips and split a speaker wire to attach to the terminals (white to positive, black to negative, etc). The only thing I can think of is on the input, it says tip negative, ring positive, sleeve ground, which I believe is the opposite of most cables nowadays.

Can anyone help me with this problem? Is the tip negative/ring positive problem causing this, or is it possibly just a faulty amp?