AM6012 vintage DAC help - modifying vintage DSP gear

[ChristofferB]

So i've gotten a mid-80's studio reverb unit that i've been messing around with, z-80 based, and has a 12 bit DAC - AM6012.

I got the idea that it'd be interesting to be able to force individual bits to 0, so that the resolution of the DAC could be lowered by forcing the LSB's to 0, or introduce glitches, but I don't understand the description in the datasheet -

 it seems that the 4 MSB's are different from the rest, needs a separate register and register clocking strobe.

Would me forcing some of these bits to 0 inhibit operation alltogether?

This is what I plan to put on a small pcb that plugs into the ADC socket, which in turn has a new socket, see attached. Of course, i'll have similar channels for all bits.

 The reason i'm not just putting a switch in line with the pins and a pull-down is that i want to have the switches on a separate 19" panel, and i dont think the DAC would enjoy 30-cm leads.

Thanks in advance!