Please, some simple info and advice

To those of you who are learned audiophiles, this may seem quite simple and trite, but this has to be the correct place to learn what I need to know. I am moving to a mono setup (klipsch corner horn, tube amp/preamp) but still need to use certain stereo equipment - CD player, tape deck, phono - in order to play favorite materials. So far, in using a "Y" connector to run the two signals from the player (CD in this case) into one pre-amp input, I seem to be getting a distorted signal. How can a person combine these two channels from the player in a way that yields good, clean reproduction from the amp? Is there a high-quality "Y" connector or some other device that does this well?

Also, in your experience, will a high quality stereo amp with center channel output enable a solution if one were to run both channel signals into the pre-amp and use the center channel as a mono output?

Or - something better?
Thaks, Cccc