There must have been several designs of the AX3-5 models, as I own AX3's, and lusted after AX5's in the late 1980's and early 1990's.
Mine are not rear firing subwoofers - they face forwards ( but I remember the AX5's as rear firing), have a square cabinet design, and came in both vinyl and veneer. Keep in mind that they may have lifetime warranties, at least mine do. That may have been changed at some point, as the design seems to have changed.
As a point of reference, I have driven mine with NAD, SIMAUDIO, YBA, tube amps, mass market stuff (Akia, Sony, Yamaha, etc), etc, and have only experienced difficulties when using the mass market low end products. I have been impressed by the sound and quality of them, and continue to use them.
