i have 2 alpine type-R 12 in subs. They are dual 4 Ohm model. Also i have an orion 600D amp. I was told that the only way to wire these 2 of these subs together was either at 4 ohm, or at 1 ohm. Is that correct? Id really like to wire them at 1 ohm since my amp is capable of 1 ohm. any advice?