What a couple of people have tried to point out is that if you are feeding the CD Player (whatever it may be) into your DAC, you are bypassing the CD Player's internal electronics, especially the Analog Electronics, and thereby eliminating any coloration the CD Player might have. The bulk of the work is done in the DAC, the better the DAC, the better the sound.
That's why people are suggesting a modest CD Player to be played through a considerably expensive DAC. It is really the DAC that will determine the sound. Used this way, the CD Player is no more than a Transport.
I assume you bought the Roksan DAC on sale, in which case you probably got it for about 1/3rd the suggested retail price. So that should be a very good DAC, far above what you paid for it.
Myself however, even if I had DAC inputs to spare, I'm content using the DAC that comes in the CD Player. If you are using the Roksan DAC, I would try it with and without that DAC to see if there is a difference.
I think your Yamaha AS801 Amp is about £600, perhaps just under, so I'm not sure a £1000 or £1600 CD Player is justified, but again, it is your money, do as you please. I know the Yamaha CD2100 is up in their Audiophile line whereas the AS801 is the top of the Consumer line. That's quite a jump in price, but each person assigns their own priorities to their system.
I don't think anyone is telling you not to buy the Roksan or the Yamaha CD Player, what we are saying is that they are out of proportion to the rest of your equipment. But that is a generalization. You get to set and follow your own priorities.
Just a few additional thoughts.
Steve/bluewizard