I had a MB Quart 4 channel amp that put out a rated 100 x 4 @ 4 ohms. I sold it and am now using a JL 300/4 which is rated at 75 x 4. Although the midrange and highs were a lot louder and cleaner with the JL, it lacked the midbass the MBQ had. Even my brother said it sounded as if I had a small sub in the back when I still had the MBQ. All the crossover settings are pretty much the same as well as the gain. No changes have been made at the headunit.

 

The gain setting is an arbitrary adjustment. It will vary from amp manufacturer to amp manufacturer. Unless you set the gains by measuring voltage output using a DMM then you have no idea how much power each amp was producing.

Same for the crossover. Unless you have an outboard crossover that did not change settings, then you don't know the exact crossover. Especially if it is just a know or screw that you adjust. You could use a spectrum analyzer to get exact measurements. Even if you get the crossover set to the same cutoff frequency, the slopes may be different.

Finally, the difference between 75w and 100w is barely enough to be audible.

-Robert