Subwoofer or Bi-Amp?

Bi Amping will improve the sound of your system within its present frequency range but, unless you are using a grossly inadequate amp, will not increase the frequency range of the speaker. It may better utilize that range, but to extend the range downward you need a dedicated subwoofer. That in where the name comes from. A good sub will add to the bass range of your system and produce a greater sense of realism whether or not very low bass is present. I use REL, HSU,and NELSON REED but there are many good ones.

What you heard was correct. If the sound is clear then the crossover point is set way too high or it is not really a subwoofer. You are adding JUST the very low frequencies and should not "hear" the sub at all. I usually can't tell if mine are on when I am standing next to them but If I put my hand on them I can feel strong vibrations. The ear is not very sensitive to direction at very low frequencies. Your description was exactly what a good sub should do.