recommendations on adding amp

Add an Audio Control Epicenter, upgrade to an Eclipse CD8443, lose the equalizer, all this will have an amazing difference in sq and output levels and depth for the subs. Just .02 cents worth of opinions.

Adding an extra amp will also increase the quality of the bass, since each amp will be dedicated to each sub.

Actually, the Epicenter needs to be connected to a full-range output, NOT a sub pre-out.  The owner's manual makes this very clear.  The way the Epicenter works is by listening for harmonics and re-creating the bass notes that created them if the bass notes are missing.  For instance, the Epicenter might detect a harmonic at 150 Hz and then check to see that the 75 Hz note that created the harmonic is still there.  If not, it will re-insert it into the music.

If you were to connect the Epicenter to a low-pass signal like a subwoofer pre-out from your deck, some the harmonics would likely be blocked before the Epicenter could detect them.

As for what model to use, there are two basic types.  The first type has a brain box with no controls on it connected via phone cord to a control knob within easy reach of the driver.  This model is called "The Epicenter", and there have been a couple different revisions of it over the years.  The other type is a half-DIN dash-mount unit that has a built-in SPL meter.  There have been two of these, the EPIC-150 and EPIC-160.  I believe the only difference between the -150 and -160 is how high the SPL meter will read.  I have both types - an Epicenter in my wife's car and an EPIC-160 in my car.  They're great, but it really depends on what you listen to most.  The Epicenter/EPIC processors make less of a difference with CDs, since there's less low-frequency content that gets lost during the recording process.  But on tapes, MP3s, or FM broadcasts, it makes a big difference.

Scott Gardner