Dark means that the treble range is lower than the mid bass energy. Dark is like the opposite of brightness in a speaker. It is the relationship of bass to the treble. Some users like a particular sound signature. The previous monitors, the Tannoys I had before the Equator were much brighter. The JBL's just have the better blend of SQ and clarity I like. I also like the Emotiva Airmotiv 6 as well. Both are very good and in use.