Thanks - yes your quite right. They were having an effect on the mains before I EQd them. The room is a horrible shape (8ft wide x 8ft tall x 16ft long) producing nasty modes. The rest of the room has sound absorbtion material and rugs on the walls.
I wanted distortion free bass - and this provides it with ease.
Need to look into making speakers but from what I have seen it gets a whole lot more complicated.