Yup. That is completely right. I also think someone else mentioned that you should be on the higher side of what your subwoofers RMS rating is, rather than the lower. That and you can even go a little over if you need to without damaging them. Also, one thing is that when you actually do the wiring itself, MANY mono-amplifiers have two sets of speaker terminals. These are there for your convenience and you should most certainly feel free to take advantage of them because they wire up the speakers the same way your picture describes.
