Harshness in a CD (presuming it is a good to very good one) may well be due to electrical interference so a cable with good regection is probably what you need. I would reccommend the Analysis Plus Copper Oval (or the new single crystal) oval or for less money and slightly less result, the TMC cables. probably a Yellow in your case they are slightly warmer than the Whites (very stiff, but if you don't need to move things much they are superb). I think the tube buffer is a bad idea in principle all you can possibly be doing is inserting noise and distortion (pleasing though they may seem).
Which cable will reduce harshness of CD player?
Have been experimenting with different copper and silver cables. My rig is all solid state and I find the CD source to be a little bright. Don't want to upgrade or downgrade or trade so I'm going to flavorize it with some IC's and SPKR cables. I tried the MF Nuvista Silver IC's and were too bright, but very pure, currently switching between Custom House and XLO. Going to try Cardas Quadlink next week. Any recommendations would be greatly appreciated.