Suggest you do more research before getting into DIY loudspeaker building. Read Floyd Toole's "Sound Reproduction" 3rd edition to learn how loudspeakers and subwoofers behave in-room. He recommends shopping for loudspeakers based on spinorama test results and use of 4 evenly spaced subwoofers. With monitors being a given, recommend looking into active designs (very dynamic) that use wave guides to control dispersion and improve imaging. Buchardt A500 and Genelec "The Ones" come to mind. And of course a proper listening room (not small or squarish, well insulated, and hopefully dedicated).