1db will make a 1db difference, not much. But the 9s should be more capable in other ways.

How high have you turned up the 3803? And have you measured the db with a meter, or is this just your ears telling you it isn't loud enough? And what is your preference. Ex: some people would consider mine to be too loud, others would say it can't go loud enough. I can hit peaks of over 110db without damaging my receiver or speakers (maybe ears, though).

Oh, I have Klipsch tower speakers with a sensitivity of 98. So my Onkyo can drive them a bit louder than your Denon can drive your 93 rated speakers. Our receivers are about the same in power. But that's still only about 5db louder, you should be able to get pretty loud, unless those smaller speakers are just running out of ability over 100db.