Most 'phile speakers are not meant to be exposed indoors to the sun, so 'under' is a terrifically bad idea to pursue.....concert PA excepted....;)
Anyone who bought 30K$ speakers 20 yrs. ago is probably listening to full boat MBL systems now, or their preferred equivalent.
Cabinet resonance will always exist; the simple physics cannot be ignored, only dealt with, unless dipole or omni. The lower frequencies can be dealt with DSP and an active system, beyond which is the placement in the given space....
Space, your final frontier. I'm working on ignoring mine for the time...ergo, the previous comment.
Welcome to the weakend, y'all. J
Don't be like me and do it in only one place... ;)