Batboard

Can I use a remote-mount Spectra with only one DB-25 connector in a dual-head setup? Can't I just build a "Y" cable and plug both heads into the same port, like a Syntor X9000?

Nope.

And the rear head is different than the front head. I managed to kill a regular head by connecting it as a second head.
The keyboard matrix is messed up..

You have to change the front plate/interface board out to the two DB25 connectors style.

Techie IS correct there are some differences between the Front and Rear A/C9 heads.

OK, thanks for the info. What head(s) is(are) compatible as a rear head? What is the part number of the front plate/interface board I need?

see http://www.open.org/~blenderm/spectra for comprehensive spectra info.

the only known rear control head is the HCN1071C (A9)