@vonhelmholtz That album is also quite psychadelic with the soundstage, which is why I shared it. :)
But slumping down so your head is on the couch will, yes, result in changes in the dispersion, but also potentially introduce reflections coming from the couch to your ears. This is especially true if your couch is made of leather.
Happy to hear of the discovery, though and hope you can adjust your speakers or listening position to deliver that level of performance consistently!