I don't know anything about DC Level 1s - but I have some strong feelings about them. Very strong feelings. The things I would do with a DC Level 1. So many things.
Anyway a simple Google search provides this: http://www.levelonedc.com/home.aspx
You are welcome!
Up to thermal limit (and this is a general rule of thumb) doubling power is worth about 3dB. Going from 1000 to 1500 isn't even doubling. 3dB is often considered just noticeable, like a click or two on the head unit.
British people have some cool slang and I am a bit jealous. I'd use their words, like calling people Savages, but in that good/funny way, but it just wouldn't work.
Sometimes you need to help yourself a bit before others can help you. Anyone who wants to help you after reading this is going to have to play 20 questions with you.