The
Omega 90 installation manual is pretty generic. All it says is use appropriate gauge wire.
As with any installation, use stranded copper automotive wire with a suitable ampacity rating based on the length of wire you will be using and the current you intend for that wire to carry. This chart was posted in
another thread on the topic:
Remember that the current will be double if you decide to use your Omega 90 with two speakers instead of one.