If you're running at 2 ohms then the 1800d would give you more power. If you do use the w6 and wire it in parallel you'd be at 2ohms but that sub only handles about 400 watts rms. Also, the 500/1 would be the cleaner amp out of those two. They're both pretty good amps but I'm not sure you should use that sub if you shooting for such a high SPL #. If you're trying to hit over 140db with one sub and you want to use JL you're going to need a w7. You could do a 10w7 on a 500/1 in a vented enclosure or 12w7 on a 1000/1. That's all if you're dead set on using JL Audio.