500 series units let build out your dream signal chain without needing a console. Here are some of the best 500 series preamps.
If you are looking for some different options for front end than what comes with your interface, these best budget channel strips are a great start.
DBX is a pro audio company that is known for creating their live sound and in studio rack mounted gear. They are best known for their compressors which can be found in studios all over the world, both professional and amateur. DBX's original goal was "to get closer to the realism of live sound".