I have acquired over the years some excellent but oldish CD Players eg; Marantz CD10, Sony X 77ES, Quad 67. I am looking to buy a used DAC to upgrade their performance. I do not want to spend a whole pile of money in case there is no real benefit - to my ears at least!. I would appreciate some recommendations-those that appear to be siutable include Dacmagic 2i, Audio Alchemy dde1 and dde3, M-Audio SuperDAC, Meridian 263 and the Flying Cow. Advice on the most suitable of these or other suggestions gratefully received.