I'm not sure on a pioneer head unit, as I don't have one. But that unit does have it high and low pass filters. It's going to be a crossover setting. You should have one that is LPF, which will affect on the sub output. This one should not matter if you don't have a sub and will not affect your regular speakers. And then there would be another setting for the front and rear, which is the high pass filter. This is the output for your regular speakers. It should be able to be set something like: off, 80hz, 160hz, 225hz. These aren't exact values but just an idea of what the various settings might be around. Make sure it is off. Otherwise you may be limiting the frequencies those speakers should get before they get to the amps.