Sounds like a bad idea to me--if the both are switched on, aren't you going to be running something strange into your amps--a balanced signal from the CD player and an SE signal from the preamp? If one is off and the other on, seems like you might be doing something like adding some weird passive element to the line level signal path, even if it is in parallel--plus I'm not sure how the XLR to SE conversion is done, but I might also worry about shorting something out.
I've tried to run sources w/volume controls direct into amps, and didn't like the result. Before you mess around too much with trying to run it direct, I'd seriously advocate some hard listening with the CD direct and CD through the preamp. It may sound like there is less in the way--and some folks seriously believe in passive attenuators or other ways of going pre-ampless--but I'm not one of them. In my case--driving VT100s from a dCS Purcell, I found the dynamics seriously compromised.
I've tried to run sources w/volume controls direct into amps, and didn't like the result. Before you mess around too much with trying to run it direct, I'd seriously advocate some hard listening with the CD direct and CD through the preamp. It may sound like there is less in the way--and some folks seriously believe in passive attenuators or other ways of going pre-ampless--but I'm not one of them. In my case--driving VT100s from a dCS Purcell, I found the dynamics seriously compromised.