Is the Pioneer your CD player? If so, you don't need to do anything different -- the left and right channels of the Pioneer's 5.1 output should carry the CD's output.

If you have a separate CD player that you want to connect to the left and right channels of the 5.1 input, I'd recommend a switch box from radio shack rather than Y connectors -- connect the left and right channels of the 45A and the CD player's left and right to the switchbox, and then the switch box to the left and right channels of the 1050's 5.1 input.

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