How would you upgrade my entry level system?

Think of it like you're building a house. First, start with a solid foundation ie. room treatments (GIK or ASC) and vibration control (Herbies has affordable options). Next. address your incoming power ie. power cords (many options out there, buy used) and outlets ( also dedicated lines of possible). Doing these things will pay off in the long run no matter what gear you get in the future. Good listening. Jeff