FWIW, I have the original miniAMBIO box and front Ambiopole simple setup for my smaller system. It’s highly effective and pleasing, at least to my ear. The box itself is quite clearly a miniDSP one.
As the subject is on enhancement of stereo beyond the usual 2 signals to 2 ‘speakers, in ambisonics (not to be confused at all with the above) one of its 3 decodes, usually available in modern DSPs, is designed for stereo and gives better frequency with direction decode than stereo, leading to enhanced stability and naturalness WRT head movement. Of course, at least 4 loudspeakers are needed and a (virtual) central listening position. This ‘enhance’ mode works nicely, but quite differently, on quad SQ as well.