Wow! HQI ballast on single ended setup. Yup, you will be close to 400W per light. The XM 10Ks you have will prolly be on the yellow side now. But par is a monster! You will have to raise those lights a bit or you may bleach out some corals. Any reason you went with HQI M80s instead of M59s? Well at least you can run Radiums if you desire. Chris, those mag ballast are pretty much all the same. When i had my old PFO HQI magnetics, I looked inside and they were made by Advance. Like a dumb arse, I traded them in for electronics. Good thing Dan traded me with his HQI magnetics. The ones I got from him are made by Hamilton. When i opened the casing up, guess whos ballast is inside? Yup, its an Advanced ballast.