Interconnect set-up from pre to 2 mono-blocks?

Do these amps have a switch to bridge the two channels into a single mono amp?
If so, then switch it to "bridged" mode, connect the speakers as the manual says and try the right input. If you hear nothing, then try the left input.

If the amp is strictly stereo, then you will need a balanced preamp and a custom cable: XLR to two RCAs (assuming the amp has RCA inputs).
Feed the positive signal (and ground) to right channel input and the negative signal to the left input.
The output is derived from the hot (positive) speaker wires og both channels. Connect the right-positive-out to the speaker-positive terminal and the left-positive-out (positive - not a mistake!) to the speaker-negative terminal.
The same can be done for an amp with XLR inputs, just a minor change to the custom cable.

every stereo amp ive ever owned that ran in bridged mono used the red(right)terminal for mono bridging.

mike

Thanks Lugnut, and yes, they are a "stereo" pair to mono.
With both units having 2 inputs, left & right. The manual doesn't give me any instructions, only the speaker cable
set-up. Even my dealer wasn't sure! Their set-up in
their store was bi-amped. I cannot go that way, as my speakers are only single-wired. Thanks, Mark

Unless I'm missing something here...if you are using true monoblocks then there will be only one input per amplifier. If you are talking about a stereo-bridged to mono amp then you would need to refer to the owners manual or simply try it each possible way.