I have a Technics SL-D3 and a Bose Wave CD player...there's the red/white cable on the record player and the red/white Aux on the Bose. But put them together and I have to turn up the volume on the Bose all the way to hear anything at all...and it's still really low volume.
I asked at two electronics stores down the street. One guys said it was impossible and offered to sell me a giant boombox that he said would work, and the other said I needed a mixer. Neither sounded like they knew more than I--and I don't know anything about this.