That is more than just possible, it is exactly what should be happening. If you put the bass management switch in any position other than BP, you are engaging a crossover network that applies a high-pass filter on the left and right speakers (removing data below the crossover point for the position that the switch is in and sending the rest to the left and right speakers) and a low-pass filter on a summed copy of that data for the subwoofer output (removing data above the crossover point and sending the rest to the subwoofer). Since you don't have a sub, the only position that you'll want to use is "BP" because anything else will simply throw away the lowest frequencies.