PreSonus ERIS STUDIO 4 Active Studio Monitor with EBM Waveguide - 4"The Eris Studio 4 sets a new standard for compact studio monitors. With its surprising amount of low end and wide, well controlled sweet spot, you can enjoy premium, accurate monitoring in even the smallest of mixing spaces. The custom designed EBM (Elliptical Boundary Modeled) waveguide provides superior high frequency response that allows you to hear the finest details in your mix, while a wide 120 degree horizontal dispersion creates a broad sweet