How to hook up my meridian 800 v3

I have an mbl preamp and dac , and am going to remove my transport , would the meridian install exactly the same way , or would I have to go into menu and tell it to activate for dac
It depends on the configuration of the 800 as there were several options. Typically, the Smart-Link 2-channel downmix jack is active for such an application.

Can I run my digital ref cable. From dac to meridian as I'm doing now with my current transport
I guess so but I do not know what your "digital ref cable" is.
MIT. Ref
If it is 75ohm (or close) RCA/coax, it will work fine.

Thanks just wanted to use the dac any other option better kal