Sounds to me like you have a hardware problem with your installation. If you need to fiddle then you've probably not selected adequate speakers for your listening patterns.

The setup I have now sounded great with the stock headunit. And I'm listening to the same music (granted in a different format). So I know the hardware is acceptable to my tastes. I just cant seem to get it to produce with the empeg.

I get pounding bass when appropriate and live-sounding voice when that's called for. All without ever having to retune anything.

I've been messing with this for weeks, and I'm still unsatisfied.
Just today I think I've almost got it doing what I want with the EQ. But even then on the way home a song came on that I felt could have used more bass. So I went into the EQ and fiddled it so it sounded right. Then a few songs later, I had to go in and set it back again. (all while driving. I'm getting really good at it! )

If you need to boost your bass at high volumes, then you're not running appropriate drivers. Or you're trying to lower the frequency of songs that were never meant to go low to begin with.

I'm not running the volume that high. I'm not trying to blow any windows out. You probably couldnt even hear the music outside the car. I just cant get it to sound right with the tools I have. I've set up the multiple EQ's and I toggle between them, but it still isnt right. And I just dont have the time to invest in sound engineering my car.
I'm not trying to win any car-sound contests. And living in Boston I have an extreme distate for the people who cruise through my neighborhood with their 150db sub-woofers that make their license plates rattle. I'm not trying to do that either.

Sigh...
My Beastie Boys are flat, and heaven forbid a song has a high-hat in it.
I'm discovering songs on a daily basis that use instruments that I had no idea were in there.

OK now I'm babbling. Off to bed!!

Z~