None. Standing waves are not defeated, just moved. Splayed walls are only good in rooms where ceilings taper too. Always shrinking with the direction of sound away from the source.

Build a rectangular room and treat the ceiling with decending polycylindrical diffusers. Room should shrink as it heads further back in height. Using suspended polys allows tweaking after the fact and backing the panels with roxul to create membrane absorption. Will upload pic later.