Have a OCM 200 power amp

Most likely for bridged mode...  OCM was / is good stuff.....

Rated Power (unbalanced stereo): 100 Watts - 8 Ohms / 200 Watts - 4 Ohms
Rated Power (balanced mono): 400 Watts - 8 Ohms

So I can use a Y cable with a XLR on one end and two RCA on the other into the preamp.....????

Wayne

So I can use a Y cable with a XLR on one end and two RCA on the other into the preamp.....????

No.

While I’m not familiar with the OCM 200, after looking at a rear panel photo on the web, and given the info provided by Jperry, it appears that what Oddiofyl said is correct. And therefore the XLR input is only for use when operating the amp in bridged mono mode, in which it would only process a single channel.

In that mode the XLR connector would be connected to an XLR output of a preamp, that would provide the amp with a balanced pair of signals for a single channel. And in that mode a single speaker would presumably be connected to the two + (red) output terminals of the amp, with the - (white or black) output terminals left unconnected.

Regards,
-- Al