Ok I'll break it down like this.

My 94 came with a tape deck w/ equilizer and the Gain control slider.
My 98 came with a cd player w/ bass and treble sliders and a Bose stick where the gain controler would have been.

I bought a ACDelco cd player w/ equilizer a long time ago for my 94 (it was out of a 98 Bonnie).

Then I bought the 98 I took the cd player out of the 94 and swapped it into the 98. The bass seems kinda loud and excessively thundering. I was thinking maybe not having a gain control had something to do with this or the that maybe the stereo amps were boosted by 98. So I did some testing by ear and it seems that the equilizer cd player in my 98 is just as "loud" as when the bass and treble sliders are set at the middle (default) position on the old stereo. When I move the sliders up it gets pretty darn amplified. I have to keep my first 2 equilizer sliders at the bottom when listening to Black Eyed Peas.

Confusing? I hope not. Just curious why this is happening. The cd player with bass/treble sliders is in the 94 and I can bring the bass down to just about nothing off the same cd. Anyone have an explanation?

Loudness button??

In my 90 if the LD button is pressed and the gain slider is on full, the speakers fart like contestants at a baked bean eating contest. Adjusting the EQ or turning the gain down restores the thump that I like.

Yup, I know what you're talking about. I put the same deck in my 99, and did some side-by-side testing with my brothers old 1992 SSE with the stock CD deck from the 99. It'* because of the internal amp on the EQ deck and also, the ohms I believe are different between the BOSE and non-bose speakers.

So basically I got a whole lotta amps for a stock setup? Mmmm...it'* gotta be the seperate amp outside the radio I'm guessing that'* totaling to more power than the 94.

I think it has to do more with the double EQ'* going on, then any power. The bose amp will only put out so much, it might even adjust for inputs. I think the bose amp you have will have an EQ setup for bass boosting on it'* own, and coupled with a HU pumping out a different equalized signal will really effect things.

Only way to know for sure is to test with white noise and some equipement...