Welcome Dan!
The most advanced loudspeakers currently available use active design, waveguides, and DSP to produce best possible imaging/soundstage with proper room interaction. Look a Dutch & Dutch 8C, Buchardt A500, Kali IN-8, and Kii 3 as examples. The engineering that goes into such products takes heavy R&D and goes miles beyond what hobbyists or one man shops can possibly come up with.
Suggest also reading Floyd Toole's "Sound Reproduction" (either edition) to learn how loudspeakers interact with rooms. Toole is well respected for the research he did at the Canadian (National) Research Council and with Harmon International. What you'll find is that bass peaks/dips can exceed 25 dB and multiple subwoofers is the best solution. And as we all know the best location for generating bass is corners/walls (opposite of the best location for generating mids/highs).
