To help me better assist you please take the time to answer the following questions for me:
1. What version of Sequel do you own and have installed? (To find this on PC open Sequel and look under Help>About Sequel) (To find on Mac open Sequel and look under Sequel>About Sequel)
2. What operating system are you currently running? (To find on Windows/PC go to Start>right click Computer and choose Properties) (To find on Mac go to the top left Apple Icon and click About this Mac)
3. What audio interface are you using with Sequel, and have you installed the latest ASIO or CoreAudio Audio driver for your operating system?
4. On the bottom tabs for preferences, in the Audio Connection, what driver do you have selected?
Steinberg US Support