StUdio

I recently bought the r-15pm studio monitors and a single r-10sw 10" subwoofer for my personal studio, ran through my computer. In order to make the most out of my sound, maximizing it's quality, I've been told that I should use an audio interface for my speakers. As of now I use the usb input to the speakers on the back of one of the monitors with the sub connected to the monitor. I wasn't sure as the speaker is connected via usb rather than the audio outputs on the back of the computer. If so, would the audio interface drastically increase sound quality?