Preamp to UA25-EX

Hoping that someone can tell me how to connect the UA25-EX to my chain. I hadn't been using it for a while but a break-in sees me back to some of my stored gear.
 
The chain is DAV preamp >> ART compressor >> Lexicon reverb >> UA25-EX. Do I have to connect via the digital in/out at the rear or do I just go into the XLR input on front?
 
Cheers,
Siog