Simple, the frequency response of the two speakers is different. The new speakers are brighter and our ears are most sensitive at 3000 Hz. If I EQ 3000 Hz up everyone's tendency is going to be to turn the volume down.
This says nothing about how the OP is measuring dB. He would have to be doing it with a meter. If he is relying on a scale say on his preamp he is making a big mistake in trying to relate both speakers as there will be differences in efficiency.
If I take any system and boost the high end people will initially gravitate towards the brighter sound even though it is not accurate. Same is true of bass. You can't realize that the music is a caricature of reality until you pay close attention to the imaging. It is highly unusual to have cymbals right in front of your face with the rest of the band in the distance on stage.