Let's start with Channel Islands Audio...
CIAudio is my own company and our mission is to build budget priced, no frills components that compete with products costing much more. We utilize carefully laidout, simple circuits with minimalist signal paths and rugged build quality.
Although it's my company, Greg Schug of Monolithic Sound does have some interest and helps with circuit designs etc.
As for Monolithic Sound...
Greg and I decided to do this line of products soon after my departure from Audio Alchemy. Although it started out with similar goals to the CIAudio line, the products are more feature laiden and will get more so as we release future products. These products are generally in the next price range up from CIAudio, but still big "bang for the buck" value.
We plan to continue with both lines and possibly even add a higher line of tube products in the future. But for now, we've got our hands full and have plans for many new products for both existing lines.
The bottom line is they are the same, but totally different

-Dusty_V-