Buy a used Kora here on Agon and be done with it.
I can't speak for the Kora having not heard it; but I can very much recomend the A21. I set mine up last Sat. and out of the box it impressed me. The first time I had a sound stage with CD (3D rather than 2D). Very analogue like. I have an all tube set-up and listen mostly to records. I don't think you'll be disapointed with the Musical Fidelity. Also, since it is limited production, if you do decide to sell it you'll probably have no trouble unloading it.
I will agree with the Trivista recommendation. I tried it for three days recently and it is extremely musical, incisive, harmonically rich and it throws a stunningly real soundstage. Now truth be told, I have not heard some of the other dacs mentioned in this thread but, I am sure they are also very good dacs. My recommendation is to try the Trivista. Most all dealers selling MF will allow an in-home audition. Respectable dealers of the other dacs should also allow in-home auditions. Then pick the one that best suits your preferences - even if you pay shipping twice. It will be worth it.
By the way, I used a cheap Pioneer DVD player as a transport and it performed very well. I suspect your Denon will be equally adept at transport duties.