paul6001,
Others have reported that the Canare 4S11 speaker cables provide a warmer presentation than most others. Very budget friendly and available from Blue Jeans and other cable companies, If you still find the brightness to be excessive, the Shiit Loki 4-band equalizer (analog) is inexpensive with a full refund if you don't like it and may well be the first thing that you should try. Lastly, the Rega Brio Integrated Amp is a good match with the LS50s and just may provide the sound that you're looking for. Good luck in your search.