I put a small stereo in my DD a while back consisting of infinity speakers and cerwin vega slim powered 12" subs. I have been surprised how nicely musical it sounds with the subs up under the front seats as I have never had subs that far forward, but the slim 12s seemed to be a one note wonder where they would sound really good on some songs and horrible on others. I have used countless digital EQs but there was always a catch to them from slow processing, glitches, or not being able to change certain things once it was programmed to where I never really did find one I liked. This has been years since I messed with one and after some looking around I found that the prices on them have come down a bunch and you can actually pick one up for around $150 so I decided to try the B2 audio six ten eq. That was last weekend and now my only complaint is that you can adjust so much I keep finding myself making small changes to it. But with a 31 band parametric eq for the input, adjustable cross overs(hp/lp/bp) and time delay as well as a 31 band parametric eq for each output. So for example I have the eq for the sub channels adjusted every 5 hz with a high Q so it only effects a small band of freqs, and because of this I have been able to correct what was missing.
While I was installing it I noticed I have a spot for a center channel, and I actually have a speaker to go there as well and now with the eq I have an extra output I could use sooo.....