While I haven't used a casio digital piano, I can answer this question, according to the manual, your cdp s350 takes a 12v dc power adapter so an equivalent 12v casio power adapter might be fine, the only thing that can change is the dc barrel jack polarity but brands usually kepp it standard, you can check the polarity by the polarity symbol that'll be on your keyboard/user manual and your power adapter. But keyboards are usually sold with the power adapter so if I were you, I'd contact the dealer and get it