A room mate of mine built an Ampzilla kit in 1975 that I got to live with for a time. Very fondly remembered driving Cizek 1s. Was JB also designer of the classic JBL integrated amp model SA660? I know he did the SAE IIICM and Dyna ST400 around the same time as the Ampzilla. I was smitten by Rectlinear IIIs when I first heard them, but not by their other models. The X was a very low efficiency largeish bookshelf model, IIRC, and sounded pretty dark to me, more like an AR3 than the III, which had more in the way of transparency to my then-young ears.