Its not about the DB output gains. Its about not underpowering his sub. This is his first stereo, and everybody that has had their first subwoofer installed knows that they drove the shÃ*t out of it. And I doubt he's going to connect a DMM to test for clipping. Of course at 1ohm it will put more strain on the amp than at 4ohm. But the amp specs say its rated for it, so the manufacturer has to stand behind it.