Disadvantages of OP amps in output stage of CD?

I was informed that "op amps" in the output stage of a CD player can produce thin, less full, and bright sound quality in the upper midrange,(which I have heard on my CD player) In addition, I was advised that these digital by-products can be reduced by taking the digital output signal from the player and feeding it into a good DAC with a discreet class "A" output stage

The CD player I have is a modded Cambridge 550C. I don't understand "HOW" this addition will or can improve the sound quality. Will it prodice a fuller and smooother midrange?? I also don't want to add another box to the system or spend $500-600 plus for a good DAC. Any advice and comments will be greatly appreciated. Thanks