Your breaking out some big heavy iron for what I assume is a background music system.
How close are the amps going to be to mixer, what kind of mixer do you have?
Are you running the amps in stereo or bridged mono, in bridged mono they will just about make it for a true 70 volt
system amp.
You will want to use a high pass filter on the system properly set for the speakers in the system as the amp has none hence why DC is part of it's model number!
If everything is close to each other you should be able to get by with Ying the inputs.
If there is some distance between the amps and the mixer maybe you would need a transformer at the amp rack to go from balanced to unbalanced.
The Crown manual shows connecting (-) to the sleeve (+) to the tip and leaving the shield float at the input when using a balanced source.
Back in the early 80's I had four DC300's and thought I had arrived!! I still have a couple D75's from that same era!