I believe that you have to use the owner's manual and it tells you to use the remote or switches on the front panel to switch from single ended input to balanced input. You have to tell the unit that you are using balanced inputs. I don't have a copy of the pre-amp's manual, but I believe I am correct.
Mark Levinson No.26 Balanced Input Question
My ML no.26 preamp has phono. It works fine with turntable (AUX2) and RCA input to CD. Yesterday I tried connect balanced input to CD player via XLR cable and no sound come out of speakers. I then follow the manual reset DIP switches on the phono boards no luck. Did I do right? Or something I missing. Please help. Thanks.