If there is a direct module equivalent to the DX7, it would be the TX816. It's not a rack unit but was meant to be ganged up to 8 deep in a custom sort of console. Each unit is about the size of a medium coffee-table book. I saw the gang-of-eight a few months ago at the Music Go Round in Burnsville, Minnesota (south of Minneapolis).Imagine, you could make unbelievable sounds and dissolve kidney stones from several streets away!I don't remember the price, around $500-600? It could still be there, if I get to that store I could see if it's still there.Got to admit it would be interesting to hear 8 DXs in parallel-mono-unison. I have a TX81Z 4-op rack unit and some of its sounds come close to the DX IMHO.mn