It is very likely that the two outputs are just two sets of connectors from the same amp, so combining them gets you nothing.
OTOH, all you really need is a decent RCA-to-XLR cable. This does not do anything except enable the connection. Not ideal. http://www.adorama.com/HOGXR134.html
One can make/buy an adapter that actually converts the signal to/from SE to/from BAL such as http://www.mcmelectronics.com/product/555-8485
OTOH, all you really need is a decent RCA-to-XLR cable. This does not do anything except enable the connection. Not ideal. http://www.adorama.com/HOGXR134.html
One can make/buy an adapter that actually converts the signal to/from SE to/from BAL such as http://www.mcmelectronics.com/product/555-8485