I don't know where it's best to start, I can say that I started on the cd player, where the anaconda vx made my jaw drop compared to the cardas golden reference/audioquest nrg-5/revelation audio labs precept II that I tried previously. I know the wadia player is a good piece and like most digital front ends, you will experience considerable steps forward with the best quality powercords on it (shunyata, elrod, purist audio, tranparent are some if the options but not the only ones, they are all however above the cardas, that much I can assure you of).
If you decide to start upgrading the pc's, then I can assure you that this upgrade will extend to your amps as soon as that first upgrade on the player is completed ... it's the only way IMO ... you need not necessarily go to the best, for example the python vx will offer most of what the anaconda vx offers for less and you can use that to get some pc's for your amps too ... but it will get pretty expensive ... that I can attest to ... but I think it was worth the results ... for the first time in my modest experience I was able to feel the music, to see into the soundstage ... all those things that I always saw others raving about ... now I understand them ... and now I cry sometimes when I listen to music that conveys the emotion it's supposed to.
Are you using the 805's with the diamond tweeters?
best of luck and let me know how it works out for you if you decide to go that route.