Flatter is better. I did some careful listening to mens and women's voices comparing the boosted bass mentioned in a previous post (which sounds closer to the bass with the CS3.5 equalizer ) versus the bass adjusted to have a flat response and guess what? Flatter is better. Women's voices are less chesty and Frank's voice is smoother.
If anyone wants to add a sub woofer to his system I strongly recommend one with the measurement and balancing tools similar to those that come with the Velodyne DD series. The auto-balancing feature is not so useful; you really have to get in there and manually adjust the phase angle, crossover frequency, crossover slope and several parametric equalizers as well as the subwoofer volume to obtain a flat response. And you need a microphone and a signal generator and software to display the measured response on a TV or computer screen. All of that comes with the DD series.
